[SOLVED!] Losing constant Internet connection on Mofi 4500 (and my mind)

Related to Router Devices ONLY
Forum rules
Use the SEARCH function for related issues PRIOR to posting for assistance.
undertowzen
Posts: 11
Joined: Thu Oct 15, 2020 11:46 pm
Has thanked: 0
Been thanked: 2 times

Re: [SOLVED!] Losing constant Internet connection on Mofi 4500 (and my mind)

Post by undertowzen » Sun Nov 01, 2020 8:04 pm

Hey so just reporting back.

First off found out a few things regarding the MTU I reported on earlier, the Sierra modems lock down the MTU of the hardware to 1430 so you will in fact have issues if you specify an MTU over 1430 - meaning you should populate 1430 all the way down the line from your modem to you client devices where you have the ability to change it manually. The MTU should get reported and hopefully automatically adopted by many devices once its set at the router but this doesn't always happen.

Secondly - continuing with the MTU - MSS clamping is required to really make sure things are sync'd together end to end, in the MOFI interface you'll find the option to enable this on the network screens on other routers you'll find it in either firewall settings or you may have to enable it via a script. On devices where you can modify the IPTables directly you can set the below config against your wan and lan interfaces, just copy paste and replace the section <wwan0> with whatever your interface name is without the < >. You'll have three entries minimum here one for lan and one for wan and the generic blanket rule - but experiment if you have additional configurations.

iptables -t mangle -A POSTROUTING -p tcp --tcp-flags SYN,RST SYN -o <wwan0> -j TCPMSS --clamp-mss-to-pmtu

I've also applied this blanket clamp rule which applies as a whole

iptables -I FORWARD -p tcp --tcp-flags SYN,RST SYN -j TCPMSS --clamp-mss-to-pmtu

Thirdly, I got away from the Mofi and onto a USB enclosure connected to a router running Golden Orb Rooter firmware. My settings here are as above when it comes to MTU and as well I've always forced DNS of 1.1.1.1/1.0.0.1 or 8.8.8.8/8.8.4.4 on my interfaces, I've also enabled QOS on Golden Orb against the wwan interface using the 0 up 0 down Cake SQM I specified in a previous post. I have TTL set to 64 instead of 65 however you may have better experience on one or the other. I'm happy to report that not only do I still have no disconnects, my once a day slow downs are gone and I have 10ms lower pings AND my download speed increased from 65Mbits to 100Mbits down - my Upload however remained the same at 17Mbits.

If anyone is curious I am on AT&T Sim through UBIFI I've had the service with them since December 2019. I am band locked to band 2 and 12 for aggregation.

I am still rebooting all my routers and the modem once a day as standard practice.

Lastly, I'm sure many of you may know but the reason why the VPN is fixing a lot of problems is because it sets itself up behind its own network with its own settings which don't necessarily interact directly with your hardware in the same way a standard network would hence why it isn't having the same problems as running without it. However I do run a VPN on one of my Merlin WRT routers for online gaming and below is my additional / custom config I've found that works best for binding the VPN to the routers/modem MTU and speeds. This gives me the highest throughput and the lowest latency for my games and downloads through my VPN client. You may want to play around with the settings.


remote-cert-tls server
resolv-retry infinite
remote-random
nobind
tun-mtu-extra 0
mssfix 1303
tun-mtu 1428
persist-key
persist-tun
ping 15
ping-restart 0
ping-timer-rem
reneg-sec 0
remote-cert-tls server
nice -30


Anyways just thought I'd pass this all along in case it helps anyone out. Good luck to everyone.

j2227
Posts: 7
Joined: Mon Nov 02, 2020 7:04 pm
Location: Central TX
Has thanked: 0
Been thanked: 1 time

Re: [SOLVED!] Losing constant Internet connection on Mofi 4500 (and my mind)

Post by j2227 » Mon Nov 02, 2020 7:18 pm

undertowzen wrote:
Sun Nov 01, 2020 8:04 pm
Hey so just reporting back.

First off found out a few things regarding the MTU I reported on earlier, the Sierra modems lock down the MTU of the hardware to 1430 so you will in fact have issues if you specify an MTU over 1430 - meaning you should populate 1430 all the way down the line from your modem to you client devices where you have the ability to change it manually. The MTU should get reported and hopefully automatically adopted by many devices once its set at the router but this doesn't always happen.

Secondly - continuing with the MTU - MSS clamping is required to really make sure things are sync'd together end to end, in the MOFI interface you'll find the option to enable this on the network screens on other routers you'll find it in either firewall settings or you may have to enable it via a script. On devices where you can modify the IPTables directly you can set the below config against your wan and lan interfaces, just copy paste and replace the section <wwan0> with whatever your interface name is without the < >. You'll have three entries minimum here one for lan and one for wan and the generic blanket rule - but experiment if you have additional configurations.

iptables -t mangle -A POSTROUTING -p tcp --tcp-flags SYN,RST SYN -o <wwan0> -j TCPMSS --clamp-mss-to-pmtu

I've also applied this blanket clamp rule which applies as a whole

iptables -I FORWARD -p tcp --tcp-flags SYN,RST SYN -j TCPMSS --clamp-mss-to-pmtu

Thirdly, I got away from the Mofi and onto a USB enclosure connected to a router running Golden Orb Rooter firmware. My settings here are as above when it comes to MTU and as well I've always forced DNS of 1.1.1.1/1.0.0.1 or 8.8.8.8/8.8.4.4 on my interfaces, I've also enabled QOS on Golden Orb against the wwan interface using the 0 up 0 down Cake SQM I specified in a previous post. I have TTL set to 64 instead of 65 however you may have better experience on one or the other. I'm happy to report that not only do I still have no disconnects, my once a day slow downs are gone and I have 10ms lower pings AND my download speed increased from 65Mbits to 100Mbits down - my Upload however remained the same at 17Mbits.

If anyone is curious I am on AT&T Sim through UBIFI I've had the service with them since December 2019. I am band locked to band 2 and 12 for aggregation.

I am still rebooting all my routers and the modem once a day as standard practice.

Lastly, I'm sure many of you may know but the reason why the VPN is fixing a lot of problems is because it sets itself up behind its own network with its own settings which don't necessarily interact directly with your hardware in the same way a standard network would hence why it isn't having the same problems as running without it. However I do run a VPN on one of my Merlin WRT routers for online gaming and below is my additional / custom config I've found that works best for binding the VPN to the routers/modem MTU and speeds. This gives me the highest throughput and the lowest latency for my games and downloads through my VPN client. You may want to play around with the settings.


remote-cert-tls server
resolv-retry infinite
remote-random
nobind
tun-mtu-extra 0
mssfix 1303
tun-mtu 1428
persist-key
persist-tun
ping 15
ping-restart 0
ping-timer-rem
reneg-sec 0
remote-cert-tls server
nice -30


Anyways just thought I'd pass this all along in case it helps anyone out. Good luck to everyone.
Hi undertowzen,

Just thought I would sign up because your posts (and this thread) have been extremely helpful in getting my At&t SIM working on the MOFI. I am a distance learning university student (ironically enough studying the challenges of remote learning) so certainly need a reliable connection for many of my team meetings.

I followed your advice for the QOS and the MSS (my highest was 1472 so I went with that). However, the following day, I experienced the usual annoying drop-out during a call. I resorted to using NordVPN a few days ago, which prevent drop-outs, but I am discontinuing my subscription due it cutting the little bit of bandwidth I have almost in half even with using the client apps. For example, Microsoft Teams repeatedly blocks my screen with a "Poor connection" banner. Without the VPN (BTW I am bandlocked to 2 and 12) I get on average of 10Mbits, with "full bars" on Mofi's connection screen.

I don't have the experience to build a custom setup like you, but I can follow tutorials. I have adjusted my MSS to 1430 and turned on clamping (previously off). I am not sure any of my other settings may be adversely impacting my connection (I typically don't mess around with settings).

I will report back as well to let you know (hopefully) the success story!

undertowzen
Posts: 11
Joined: Thu Oct 15, 2020 11:46 pm
Has thanked: 0
Been thanked: 2 times

Re: [SOLVED!] Losing constant Internet connection on Mofi 4500 (and my mind)

Post by undertowzen » Tue Nov 03, 2020 1:59 pm

j2227 wrote:
Mon Nov 02, 2020 7:18 pm
Hi undertowzen,

Just thought I would sign up because your posts (and this thread) have been extremely helpful in getting my At&t SIM working on the MOFI. I am a distance learning university student (ironically enough studying the challenges of remote learning) so certainly need a reliable connection for many of my team meetings.

I followed your advice for the QOS and the MSS (my highest was 1472 so I went with that). However, the following day, I experienced the usual annoying drop-out during a call. I resorted to using NordVPN a few days ago, which prevent drop-outs, but I am discontinuing my subscription due it cutting the little bit of bandwidth I have almost in half even with using the client apps. For example, Microsoft Teams repeatedly blocks my screen with a "Poor connection" banner. Without the VPN (BTW I am bandlocked to 2 and 12) I get on average of 10Mbits, with "full bars" on Mofi's connection screen.

I don't have the experience to build a custom setup like you, but I can follow tutorials. I have adjusted my MSS to 1430 and turned on clamping (previously off). I am not sure any of my other settings may be adversely impacting my connection (I typically don't mess around with settings).

I will report back as well to let you know (hopefully) the success story!
WIth VPN you will experience a few annoyances

1) Yes your bandwidth will be restricted IF you do not have a powerful enough computer or router to power the connection. VPN uses a secure protocol which requires encryption decryption when sending all traffic and this requires CPU power to process.

Its understandable that buying an entire brand new computer is not idea just to power a VPN client connection but maybe buying a brand new router is? Most routers don't have an additional processor built in to handle this processing but the cheapest you'll find that does will be the Asus RT-AC86U router. You can purchase this router between $100-$150 on eBay and you will be able to get up to 200mBps with it. Possibly more even.

2) Tech companies know about VPN providers and dislike them. They don't want anyone hiding you away from them when using their services so they will try to actively block the ip address range of the VPN provider or at least limit the provider access in some way. The more popular the VPN service the more likely you are to run into this situation, NORDVPN being one of the most popular you'll see this happen more often then not. I personally use Nord myself but I only use it from Gaming and a few other services I don't use it for day to day usage due to this limitation, for instance streaming services and Nord do a dance constantly where they block and unblock each other its annoying.

Custom build

This is quite simple really. What I will say is this, I feel what you are paying for with the MOFI is really their custom interface which allows you to control the modem elegantly - this new setup is a lot cheaper (about $100 for everything) and faster - but you have to learn how to control certain parts of the modem issuing commands to it without a GUI doing it for you. Its not hard I put a guide down below including where to find the commands but just be aware, if you aren't comfortable working in a DOS Terminal CLI environment it may be daunting at first. Good luck!

1) Buy a Dell Sierra EM7455 DW5811e from ebay for about $30

https://www.ebay.com/itm/Dell-Sierra-Wi ... SwZ7RdglZh

2) Buy an enclosure for the modem for between $20-$50 I personally bought the below

https://www.ebay.com/itm/Dual-Q-M-2-NGF ... 2749.l2649

3) You will need to transform the Dell Sierra into a Generic Sierra modem so follow these instructions, you will need to create a Ubuntu 18.04 LiveUSB and boot your computer from it

https://www.ttl.one/2018/07/sierra-wire ... m74xx.html

4a) For Golden orb you can buy an Asus AC66U from ebay for about $30 to flash - or a raspberry pi 3 b plus for about $50

https://www.ebay.com/sch/i.html?_from=R ... c&LH_BIN=1

4b) Or you may have a compatible router or raspberry pi laying around to flash already

https://www.ofmodemsandmen.com/routers.html

https://www.ofmodemsandmen.com/firmware.html

https://www.ofmodemsandmen.com/documentation.html

5) Once you have everything done you connect the modem to the router or raspberry pi, pop in your SIM from the MOFI, and power everything on. You should get a connection without doing much and be on your way however you will want to band lock and such so you can follow this guide here on how to issue the command to do what you want

viewtopic.php?t=33

j2227
Posts: 7
Joined: Mon Nov 02, 2020 7:04 pm
Location: Central TX
Has thanked: 0
Been thanked: 1 time

Re: [SOLVED!] Losing constant Internet connection on Mofi 4500 (and my mind)

Post by j2227 » Tue Nov 03, 2020 5:23 pm

Thank you @undertowzen for your time and collection of resources! Despite the change I made the other day, the connection is still being dropped on the Mofi. It appears mainly during heavy usage (like video conferencing and long "searching sessions" on Google. I see the affordability and relative ease in making a custom setup now. My computer is brand new (10th gen Core i5 with 16GB RAM) so I don't see limitations for encryption being on the device. I am, however, unclear of the real problem at hand that will be solved by going will a homemade router. Hopefully a list of question for you will help me understand better. :D

- What is AT&T doing why connections are dropped?
- What makes the Mofi aware that the connection is dropped?
- Did you get it fully working on the Mofi before switching to a custom setup? Should I do a factory reset and/or specifically address any particular settings (QOS, MSS, etc.)?
- Does your custom setup allow for "tower locking"? (I think this was brought up here on the forum once) It might not be something particularly necessary, but the idea sounds good at first glance.

I thought I should add that I have a DLink DIR-826L router already that I bought a few years ago. Its in the closet collecting dust, but it worked great then out of the box. I have been using the Mofi router since going with LTE.

Kindest,
Justin

undertowzen
Posts: 11
Joined: Thu Oct 15, 2020 11:46 pm
Has thanked: 0
Been thanked: 2 times

Re: [SOLVED!] Losing constant Internet connection on Mofi 4500 (and my mind)

Post by undertowzen » Tue Nov 03, 2020 7:29 pm

j2227 wrote:
Tue Nov 03, 2020 5:23 pm
Thank you @undertowzen for your time and collection of resources! Despite the change I made the other day, the connection is still being dropped on the Mofi. It appears mainly during heavy usage (like video conferencing and long "searching sessions" on Google. I see the affordability and relative ease in making a custom setup now. My computer is brand new (10th gen Core i5 with 16GB RAM) so I don't see limitations for encryption being on the device. I am, however, unclear of the real problem at hand that will be solved by going will a homemade router. Hopefully a list of question for you will help me understand better. :D

- What is AT&T doing why connections are dropped?
- What makes the Mofi aware that the connection is dropped?
- Did you get it fully working on the Mofi before switching to a custom setup? Should I do a factory reset and/or specifically address any particular settings (QOS, MSS, etc.)?
- Does your custom setup allow for "tower locking"? (I think this was brought up here on the forum once) It might not be something particularly necessary, but the idea sounds good at first glance.

I thought I should add that I have a DLink DIR-826L router already that I bought a few years ago. Its in the closet collecting dust, but it worked great then out of the box. I have been using the Mofi router since going with LTE.

Kindest,
Justin
From my perspective the Mofi hardware is really only built with cat 3 lte speeds in mind therefore it doesn’t need to be very robust. Cat 3 speed is only 100mbit which is why the mofi only comes equipped with 100mbit Ethernet ports and wireless n WiFi. They put a cat 6 modem Sierra 7455 in the mofi for whatever reason even though it could never take full advantage of it. Cat 6 lte is 300mbit by the way. Due to being underpowered and quite old in terms of when it was built I guess expectations and technology has changed, lte is better, consumer hardware is better and cheaper, etc....

Out of the box with no changes at all I only received between 5-20mbit down with my mofi depending. I replaced both antennas immediately with these from amazon and got up to 60mbit down. After swapping modems and clamping mss on all my hardware I’m now up to 100mbit. I’m going to add a booster soon and then I guess I’ll be satisfied.

"Wilson Electronics Pole Mount Panel Antenna 700-2700 MHz, 50 Ohm (314453)" https://www.amazon.com/dp/B01F3W8VC8/re ... UTF8&psc=1

1) In my situation AT&T isn’t causing it
2)In my situation the mofi router is aware because the misconfiguration of the router and modem out of the box is causing what is known as buffer bloat in top of packet loss due to the MTU settings - this causes the router and modem to just stop talking hence the disconnection
3) Yes I did get it working eventually, this all off top of my head it isn’t connected anymore

-Enabled SQM QOS with 0 up 0 down —- this however isn’t entirely correct for most situations what you should do is run a test on Speedtest.net test with this turned off and then set the upload setting to 95% of your download speed from speed test and then the download setting to 95% of your upload speed from speed test (mofi has this setting backwards).
-Set the second tab to Cake and then Piece of Cake or Layer Cake
-third tab set to Ethernet overhead with somewhere between 22-44 bytes


Set MTU to 1430 everywhere you can find a setting for this, disable auto detect MTU and auto detect MSS. Set MsS to MTU minus 40 so in your case it would be 1390.

I’m band locked to band 2 and band 12.

I disabled the firewall and WiFi and port forwarding and everything basically because I’m not using the mofi as a router.

Enable mss clamp in general network settings

I have DHCP disabled and I have a static IP set on my actual router

That’s everything I can think of that I did, after about 24-36 hours I would start to slow down but not disconnect so I would still set a scheduled reboot to once every 24 hours for not just the mofi but my entire network

4) No unfortunately I have no idea how you could tower lock without maybe yagi antennas which are directional point at the tower of choice.

j2227
Posts: 7
Joined: Mon Nov 02, 2020 7:04 pm
Location: Central TX
Has thanked: 0
Been thanked: 1 time

Re: [SOLVED!] Losing constant Internet connection on Mofi 4500 (and my mind)

Post by j2227 » Tue Nov 03, 2020 10:41 pm

Great information @undertowzen and thank you again! I will leave with the knowledge and resources you provided and see if I can tackle first upgrading my antennas (up from 5mbps to 60mbps ?!?! That's better than what I was getting with my $180 Verizon plan this time last year!) and eventually going with a custom setup! I will pass along some questions to you, no doubt, when they arise and hopefully you can help when you have time. :D Hope others can gain some insight from this.

User avatar
terryjett
Posts: 395
Joined: Tue Sep 24, 2019 10:42 pm
Location: Far Side
Has thanked: 98 times
Been thanked: 85 times
Contact:

Re: [SOLVED!] Losing constant Internet connection on Mofi 4500 (and my mind)

Post by terryjett » Tue Nov 03, 2020 11:10 pm

I would like to kindly remind folks to buy from ltefix.com when possible. I know they do not have everything on ones list of goodies, but check them out before buying from others.

Without ltefix.com there would be no ltehacks.com

Just a friendly reminder...

j2227
Posts: 7
Joined: Mon Nov 02, 2020 7:04 pm
Location: Central TX
Has thanked: 0
Been thanked: 1 time

Re: [SOLVED!] Losing constant Internet connection on Mofi 4500 (and my mind)

Post by j2227 » Wed Nov 04, 2020 9:08 am

terryjett wrote:
Tue Nov 03, 2020 11:10 pm
I would like to kindly remind folks to buy from ltefix.com when possible. I know they do not have everything on ones list of goodies, but check them out before buying from others.

Without ltefix.com there would be no ltehacks.com

Just a friendly reminder...
That's a great suggestion for noobs like me, especially with the extensive collection of experts on here open to answering our question/pleas. :lol: Thank you.

I also noticed that this thread referenced the same situation with AT&T mentioned here. I am beginning to see that the pandemic and increased number of users needing internet on the road bring to light many of the issues I have experienced over the years. I guess I have to really research this site now.

viewtopic.php?f=15&t=1906

User avatar
BrentV
Posts: 58
Joined: Mon Jun 17, 2019 11:26 am
Has thanked: 6 times
Been thanked: 1 time

Re: [SOLVED!] Losing constant Internet connection on Mofi 4500 (and my mind)

Post by BrentV » Sun Nov 08, 2020 9:09 am

This issue still persists for me. I've used Mofi and We826 Goldenorb/Wifix routers for about 4 years now. It wasn't until ATT started cracking down on the ipad plans this year that the random disconnects became an issue. Sometimes it will come back up within about a minute, other times and becoming more frequent i have to reboot the Mofi/Rooter router. Seems to happen every few hours. I've tried MTU 1430 and the MSS 1390. I don't use WIFI, firewall, etc. If it's not something on ATT's end then did something changed with their network that's suddenly causing a lockup? I don't understand why the issue hasn't appeared until recently and is only affecting ATT connections. I also had disconnects when tethering an android over USB also, although I didn't test it too extensively.

Also for those using a VPN as a workaround, are you using the VPN directly on the MOFI or on individual devices / external router? I have a Mofi being used basically as a modem and then an Asus AC66 behind that.

Someone posted this https://forums.att.com/conversations/ot ... 542c96b341 in another thread, seems like it could be the same issue?

undertowzen
Posts: 11
Joined: Thu Oct 15, 2020 11:46 pm
Has thanked: 0
Been thanked: 2 times

Re: [SOLVED!] Losing constant Internet connection on Mofi 4500 (and my mind)

Post by undertowzen » Mon Nov 09, 2020 1:57 am

BrentV wrote:
Sun Nov 08, 2020 9:09 am
This issue still persists for me. I've used Mofi and We826 Goldenorb/Wifix routers for about 4 years now. It wasn't until ATT started cracking down on the ipad plans this year that the random disconnects became an issue. Sometimes it will come back up within about a minute, other times and becoming more frequent i have to reboot the Mofi/Rooter router. Seems to happen every few hours. I've tried MTU 1430 and the MSS 1390. I don't use WIFI, firewall, etc. If it's not something on ATT's end then did something changed with their network that's suddenly causing a lockup? I don't understand why the issue hasn't appeared until recently and is only affecting ATT connections. I also had disconnects when tethering an android over USB also, although I didn't test it too extensively.

Also for those using a VPN as a workaround, are you using the VPN directly on the MOFI or on individual devices / external router? I have a Mofi being used basically as a modem and then an Asus AC66 behind that.

Someone posted this https://forums.att.com/conversations/ot ... 542c96b341 in another thread, seems like it could be the same issue?
I personally couldn’t say as I’ve been on an AT&T plan through Ubifi for a year and it’s been problematic since day 1 for me until I ran through all the stuff I did to determine what worked best for my situation. I’m guess Ubify and a few other resellers have special business plans not impacted by the iPad unlimited plan changes.

As for where to run the VPN I would suggest it would be much better to run on your PC versus your router. I have your router as well and it lacks the chip I mentioned the 86u has so it will be crippled by VPN connection. It’ll work but you’ll have high latency and a slow connection.

With that said the upside to running on your router is it’ll cover 100% of the devices connected to it whereas running on your PC or phone would only cover those devices and nothing else, so that is the trade off.

The ASUS 86u runs on the low end of $150 on eBay but handles vpn like a champ as it has the processor built in to handle the encryption decryption processing.

Post Reply