Modem Disconnecting

Sierra Wireless AirPrime Modem Card Topics
Mchccjg12
Posts: 9
Joined: Tue Sep 18, 2018 6:40 pm

Re: Modem Disconnecting

Post by Mchccjg12 » Sat Oct 06, 2018 8:23 am

Sorry it took so long to reply! I've been a bit busy lately. Anyways, I have found some interesting stuff by really scrutinizing the logs. So, it seems recently the IP address started to change after the modem gets disconnected from the network... for example:

While the network is connected and working well:

Code: Select all

At+cgcontrdp
+CGCONTRDP: 1,5,r.ispsn,173.123.203.129,,68.28.31.30,68.28.31.31
+CGCONTRDP: 2,6,otasn,25.224.104.62,,68.28.208.215,68.28.195.150
(And yeah, the OTA APN didn't last long on the results, I got lucky to catch it when it appeared, as when I issued the command after, it only returned the first line, showing the OTA APN wasn't on the modem anymore.)

After my internet is down, but while the modem is connected to the network:

Code: Select all

At+cgcontrdp
+CGCONTRDP: 1,5,r.ispsn,173.127.112.56,,68.28.31.30,68.28.31.31
There is a difference in IP addresses, which didn't happen before from what I noticed. Also, running AT!SCACT=1,1 returns:

Code: Select all

AT!SCACT=1,1
+CME ERROR: no network service
It seems to also appear in the system log without a connection monitor, as this appears in the log when it happens:
Sat Oct 6 13:13:44 2018 user.notice MBIM Monitor: Modem 1 Connection is Down (activation state: deactivated)

So no dice there. I really do appreciate all of the help by the way!

jstever8
Posts: 2
Joined: Fri Dec 21, 2018 6:41 pm

Re: Modem Disconnecting

Post by jstever8 » Sat Jan 26, 2019 1:13 pm

So I have been having a very similar issue with my EM7455 (running latest Generic firmware) in an external USB enclosure connected to a Raspberry Pi 3 B+ (latest Rooter GoldenOrb firmware) running Sprint. My disconnects were happening about every 5-10 minutes or so.

I believe I have narrowed the issue down to only occurring while the modem is connected to B41. I locked the band to 25 and went an entire day without a disconnect. As of now, I have reenabled B41 and disabled CA. So far no disconnects! I have also noticed that the temperature of the modem gets quite a bit higher when B41 2xCA is active.

At first, I thought this could be a power related issue. According to the EM7455 data sheet, the highest power draw for the device would occur with B41+B41 CA as well as low signal. The power draw for the EM7455 alone is over 1A in that particular case. The Raspberry Pi is supposedly limited to 1.2A combined through it's USB bus. This led me to try a very robust power supply (capable of multiple 5V 3A outputs) with a USB Y-splitter cable to provide the additional power the device might be needing. I also upgraded the usb cable to a very short cable with a 24AWG power wire inside. Unfortunately, no dice. Still getting consistent disconnects.

Is it possible that the disconnects are related to the modem getting too hot? I am running out of ideas as to what could be the cause. I'm not convinced that Sprint is not kicking the modem off the network as I would assume it would apply to all bands and not only B41.

EDIT: It appears others are also having issues with B25 and B26, so it may not be isolated to B41 for everyone.

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JimHelms
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Location: DFW Texas
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Re: Modem Disconnecting

Post by JimHelms » Sat Jan 26, 2019 2:20 pm

You may try changing the MTU value.

swwifty
Posts: 380
Joined: Thu Aug 30, 2018 8:21 pm
Location: NE GA Mountains

Re: Modem Disconnecting

Post by swwifty » Sun Jan 27, 2019 7:16 pm

B41 is awfully close to the 2.4ghz unlicensed spectrum. Are you by chance using 2.4ghz wifi on your Rapsberry PI? If so, try and maybe switch to 5ghz and disable 2.4ghz and see if that makes a difference.

I'm wondering if these two bands are interferering with each other, since they are so close.

MrEdLu
Posts: 2
Joined: Wed May 15, 2019 8:03 am
Location: Commack, NY

Re: Modem Disconnecting

Post by MrEdLu » Wed May 22, 2019 1:22 pm

I'm new at this and am experiencing the exact same issue with loosing internet and RRC state showing RRC Idle

Has anyone resolved this yet?

My equipment
  • WE826 running GoldenOrb 2019-03-10
  • Dell Sierra Wireless DW5811E EM7455 Qualcomm WWAN NGFF Card (REV A01) 3MDGK. Flashed to Generic 02.30.01.01 with autoflash-7455.sh
  • 12v 3a power adapter

sungpark
Posts: 2
Joined: Mon Jun 17, 2019 12:16 pm

Re: Modem Disconnecting

Post by sungpark » Mon Jun 17, 2019 1:19 pm

Hello, I am new to the forum and did the setup rooter firmware router with em7455 on sprint network. I'm also having issues with intermittent sprint internet connection issues similar to other users having in this forum.

My setup:
- TP-link Archer C7V4 flashed with GoldenOrb 2019-03-10 firmware
- Dell Sierra Wireless DW5811E EM7455 Qualcomm WWAN NGFF Card (REV A01) 3MDGK. Flashed to Generic 02.30.01.01 with autoflash-7455.sh (exactly the same as the user 'MrEdLu')
- USB To NGFF M.2 Key B Adapter Enclosure With SIM Card Slot
- In the rooter router setup, Modem APN set to 'r.ispsn'. All other settings are default.

Two things I would like to try out to resolve the em7455 data connection issues.
- Latest sierra wilreless EM7455 generic firmware 02.30.03.00 is available. Should I upgrade the firmware? If so, what is the process? Using 'GitHub' method of automated flahsing using Ubuntu was really hard for me. If someone could post the step by step EM7455 firmware upgrade process, I would really appreciate it (but is this necessary?).
- M.2 adapter usb cable upgrade: I orderded micro usb cable with 20 awg wire, which I will try out when arrives. Some people are using powered usb cable (can someone provide me more info?). What is a better option, and will cable upgrade really help with my connection issues? FYI, sprint signal is very strong in my house.

Any help will be greately appreciated. Thank you in advance.

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JimHelms
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Re: Modem Disconnecting

Post by JimHelms » Mon Jun 17, 2019 4:34 pm

Can you not remove the SIM from the EM7455 enclosure, and install the Sierra Wireless software for Windows, and flash the EM7455 with generic exe firmware.

The USB micro cable that comes with the black M.2 enclosure is straight trash. And, it does cause a lot of issues related to disconnects. Your new cable may correct your problem.

sungpark
Posts: 2
Joined: Mon Jun 17, 2019 12:16 pm

Re: Modem Disconnecting

Post by sungpark » Mon Jun 17, 2019 6:41 pm

Jim,

Thank you for the prompt response. Regarding the EM7455 generic firmware upgrade, can I just run exe file with EM7455 enclosure connected to the windows PC? To create accessible com port for EM7455, I originally tried installing usb driver (downloaded from sierra wireless) for windows, but failed. Then I tried GitHub autoflash script from Ubuntu, which worked. I'm afraid that I might brick EM7455 installing firmware from windows. If you could provide a quick step by step installation process, I would really appreciate it.

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