MC7455 and ROOTer - Troubleshooting Connection Issues

How To Tutorials related to Routers and Firmware
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JimHelms
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MC7455 and ROOTer - Troubleshooting Connection Issues

Post by JimHelms » Sun Apr 01, 2018 3:47 pm

This tutorial will help troubleshoot and resolve connection related issues when using the Sierra Wireless MC7455 with GoldenOrb | ROOter firmware on a custom built router. The information below assumes you have done a proper installation of the router firmware.

There are several common causes related to no connection and/or re-connections. Each of these should be checked where applicable.

1. The SIM Card is bad, worn or dirty from swapping it in and out of devices. Check it closely for any sign of damage. Try cleaning the SIM Card’s electronic chip with an alcohol pad and refrain from touching the metal chip area during re-installation.

2. The SIM Card is not seating properly in the SIM Card Adapter and therefore, the router. All the tits/tabs on the four sides of the SIM Card MUST be removed—sand them flat using an Emory board or sand paper laid flat on a table. Then, clean the SIM Card’s electronic chip as explained above. The SIM Card must fit into the adapter with ease, not loose but not tight. Otherwise, when pushed into the router, the SIM Card tilts ever so lightly on one end and causes the pins not to make adequate contact with the electronic chip. This bad connection can worsen as the router warms up.

3. A U.FL pigtail connector has popped off the MC7455 antenna connector port during the reassembling of the router. Or, was accidentally connected to the MC7455’s GPS port as opposed to the Main and Aux antenna ports.

4. A USB to Mini PCI-E Adapter Enclosure is being used with the stock/OEM USB power cable. They will not handle the power required for the MC7455. Replace it with a short, hefty wired, USB power cable.

5. RP-SMA antennas are being used on SMA Antenna connectors. While they resemble one another, they are different and are not interchangeable.

6. The cell tower signal strength is weak or inadequate to utilize. Relocate the router and/or consider upgrading its stock antennas to better and/or external antennas.

7. The wrong or misspelled APN is entered or being used on the router. If using a SIM Card from a phone, tablet or hotspot, reinstall the SIM Card into its original device. Login to the device and verify the correct APN in its settings. While there, update the user profile and any other software or setting available. If the wrong APN has repeatedly hammered the carrier, there is a chance it has been de-registered (for lack of a better term) from the carrier's network. Updating the user profile will generally resolve or restore it.

8. Not using the Sierra Wireless Generic firmware on the MC7455 modem.

9. A power adapter/source that is not providing enough voltage and/or amps to supply the modem when under load. The modem's power requirements increase as quality and signal strength decrease. When signals are poor, the modem attempts to compensate by increasing its transmitting power--which may utilize more current than is available.

10. The barrel tip of the power adapter plug is the wrong size. The WE | WG routers using the round tip uses a 2.1mm (center hole) x 5.5mm (outside) tip. It is also a positive polarity adapter. The 2.5mm x 5.5mm is a common power adapter tip, and is often hard to distinguish from the smaller 2.1mm center hole. Worse, a lot of sellers list the 2.5mm as being 2.1mm tips. One way to test them, is to wiggle the tip at the router while running. If the lights flicker or router reboots, chances are you are using the wrong adapter. Thus, always check the polarity of a power adapter which is generally marked in symbol form on the power adapter housing:

AC_adaptor_polarity.png



CHECK THE CORRECT APN HAS BEEN ENTERED

The first item to verify is that the APN is correct. We will check it through ROOter’s web user interface (LuCI) as shown below (it is shown using a Sprint APN, not necessarily yours):

APN.png

Make sure your APN is entered and spelled correctly, and that there are no empty spaces entered after the APN. DO NOT FORGET to hit the SAVE button at the bottom of the page. ALL changes in ROOTer must be SAVED and some take effect only when the router is rebooted.

IMPORTANT: This is the ONLY place the APN is entered when setting up the router firmware. If any other interfaces have been modified and/or the APN was previously entered in a different location, I suggest you stop and reset the firmware to its default settings (and, when back online, repeat the step above):

Reset to Defaults.png


CHECK TO ASSURE THE ROUTER IS DETECTING THE MC7455

At this point, it is useful to know if the firmware is detecting and/or attempting to connect and/or connected to the MC7455:

Attempting to Connect.png



CHECKING THE SIM CARD CONNECTION

One of the first items to check is whether the router is reading the SIM card correctly. As shown on the image below, we will run the following commands (one at a time, always waiting for it to respond before entering the next command):

Code: Select all

at!entercnd="A710"
at+cpin?

Check SIM Card cpin.png


If the at+cpin? returns anything but "READY" your issue is with the SIM Card or installation.


CHECKING THE SIGNAL STRENGTH

Next, we will test the for cellular signal strength with running the follow commands:

Code: Select all

at!entercnd="A710"
at!gstatus?
HELPFUL HINT: Any major changes to a Sierra Wireless modem, initially requires permission using:

Code: Select all

at!entercnd="A710"
The permission is required only once during the same programming session. Anytime the modem is rebooted or powered on, the permission must again be entered prior to entering AT Commands. There are also AT commands to return various information about the modem and its connection. Using the permission command will return more detailed information for the AT command.

Signal Strength.png

You will notice that there are two sets of important data here. The top section shows if it is connected to the network, whether it is registered, the Band and other detailed information. It also shows the primary and secondary (if any) serving cell.

In the lower box we will notice:

Code: Select all

PCC RxM RSSI: -67
PCC RxD RSSI: -66
SCC RxM RSSI: -78
SCC RxD RSSI: -76
The PCC (primary component carrier) RxM corresponds to the Main ("M") antenna port on the modem while the RxD corresponds to the Diversity ("D") antenna port on the modem (the AUX port on the MC7455). The RSSI (Received Signal Strength Indicator) shows both Main and Diversity antenna ports are receiving signals. This is a good indication that the U.FL pigtail connectors to the modem antenna ports are still in place and properly connected to the MAIN and AUX ports (and not the GPS port). We can also assume adequate connections between our antennas, coax cables and connectors.

The SCC (secondary component carrier) is used for carrier aggregation (CA) and are not required for a connection. The SCC stats may or may not be present depending on if the modem is idle (inactive) and/or if CA is available at your location. If SCC is not displaying in the stats, try running a speed test, downloading a file, or playing a YouTube video. It may then appear.

The lower section further details the signal strength. In order to determine if your signal strength is adequate, refer to the cheat sheet below. Note that the modem cannot connect or stay connected to a signal where none or little exists.

Signal Readings.png

If you are showing below acceptable signal levels, move the router to a different location and test again. If you are unable to improve the signal strength, consider purchasing better and/or external antennas that cover the bands and frequencies required for your carrier.

RESETTING THE MC7455 TO OEM STATUS

If the steps above were followed and each checked out, and you are still having issues connecting to the internet, restoring the MC7455 to its OEM settings, and re-configuring manually may solve the issue. This is especially true if the MC7455 has previously been installed behind another router and/or Windows PC.

To restore the MC7455, run the following commands:

Code: Select all

at!entercnd="A710"
at!RMARESET=1
at!reset
After the last command was issued, wait a second or two and perform a hard reboot of the device by unplugging the power, waiting a few seconds, and plugging the power back in.

When we reset the MC7455, it places the modem in QMI composition. We will now reconfigure the MC7455 to MBIM, and program the modem with the other specifics while we are at it. Once the router is back online, enter the following commands (replacing the ipv4v6 APN with that required by your carrier, a common APN list is included below):

Code: Select all

at!entercnd="A710"
at!usbcomp = 1,1,1009
at!selrat=06
at!custom="IPV6ENABLE",1
at+cgdcont=1,"ipv4v6","r.ispsn"
at!reset

Perform another hard reboot. When it comes back online, you should hopefully have a connection.

If you still have no connection, and ONLY AFTER trying the steps above,

1. Reset the firmware to its defaults
2. Do a hard reboot
3. When back online, enter the APN and SAVE.
4. Do a hard reboot.
5. Chances are within a minute you will connect.

* A few of the more common carrier APN’s are provided below: Some devices and/or services are limited to an IPV4 address, where others receive IPV6 and/or both IPV4v6 (dual stack). We generally use the IPv4v6 address for most carriers in the US without issue.

AT&T:

Code: Select all

at+cgdcont=1,"ipv4v6","broadband"
Verizon

Code: Select all

at+cgdcont=1,"ipv4v6","vzwinternet"
T-Mobile

Code: Select all

at+cgdcont=1,"ipv4v6","fast.t-mobile.com"
Sprint

Code: Select all

at+cgdcont=1,"ipv4v6","r.ispsn"
Sprint

Code: Select all

at+cgdcont=1,"ipv4v6","n.ispsn"
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moonunit0103
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Re: Troubleshoot Connection Issues with MC7455 and ROOTer

Post by moonunit0103 » Tue Apr 03, 2018 3:52 pm

Are there AT Commands to enable COM Ports along with MBIM? I am not sure about other Windows versions, but Windows 10 64Bit, if you have the MC7455 drivers installed in a USB adapter with everything running fine while connected to a ROOter, then connect to a Windows 10 PC, it switches the COM ports to a USB Connection of some kind, switching from #8MBIM + COM Ports to #9 MBIM only, which then will not work. This has happened to me, and I corrected it by going through UBUNTU. It took a while to download UBUNTU and make it bootable, using ISO.

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JimHelms
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Re: Troubleshoot Connection Issues with MC7455 and ROOTer

Post by JimHelms » Wed Apr 18, 2018 7:57 am

moonunit0103 wrote:
Tue Apr 03, 2018 3:52 pm
Are there AT Commands to enable COM Ports along with MBIM?
If the "Modem" COM port is available the following command places the modem in MBIM composition:

Code: Select all

at!entercnd="A710"
at!usbcomp = 1,1,1009
I am not sure about other Windows versions, but Windows 10 64Bit, if you have the MC7455 drivers installed in a USB adapter with everything running fine while connected to a ROOter, then connect to a Windows 10 PC, it switches the COM ports to a USB Connection of some kind, switching from #8MBIM + COM Ports to #9 MBIM only, which then will not work.
By default, Windows 7 uses QMI composition while Windows 8 and 10 uses MBIM. While using the Sierra Wireless generic driver software for Windows (allowing Windows to communicate with the modem) does not generally create an issue, I have noticed certain instances and programs (i.e., Sierra Wireless Skylight Manager) that place the modem in an undesirable composition with no Modem com port. This seems to be happening more often and I am really not sure why.
This has happened to me, and I corrected it by going through UBUNTU. It took a while to download UBUNTU and make it bootable, using ISO.
Yes, Ubuntu seems to work well in handling various tasks on Sierra Wireless modems. I am a Windows user by default and I am not very proficient with Linux. I do have an Ubuntu virtual machine using VMWare workstation that I use on occasion--but certainly not as much as I should.

We did have some good Linux users and tutorials on the previous Hacks forum. Hopefully, in time, we have more.

shroudedninja
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Re: MC7455 and ROOTer - Troubleshooting Connection Issues

Post by shroudedninja » Fri Jun 15, 2018 4:10 pm

Thanks for this guide. I'm trying to work through each of these points step by step.
A power adapter/source that is not providing enough voltage and/or amps to supply the modem when under load. The modem's power requirements increase as quality and signal strength decrease. When signals are poor, the modem attempts to compensate by increasing its transmitting power--which may utilize more current than is available.
I'm currently using WG3526 with PoE mounted outside and two omni directional external antennas. The signal around my house is low to moderate (heavily wooded area). My WAN connection drops 3-4 times a day and often requires me to reboot the router. Is it possible that PoE isn't providing enough power? Is there a way to tell if I'm not getting enough power?

I took a couple of screenshots with my connection details a while ago, I can get some more up to date ones if needed:

EDIT. Attaching images directly instead of external link

On Band 26
Screen Shot 2018-05-19 at 11.42.18 AM.png

On Band 41
Screen Shot 2018-05-19 at 11.31.30 AM.png
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JimHelms
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Re: MC7455 and ROOTer - Troubleshooting Connection Issues

Post by JimHelms » Fri Jun 15, 2018 5:32 pm

Can you please include your screen shots on your post as opposed to a link. That will assure the image will be available in the future for members to view as we attempt to work though the issues.

shroudedninja
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Re: MC7455 and ROOTer - Troubleshooting Connection Issues

Post by shroudedninja » Fri Jun 15, 2018 6:12 pm

Edited my post to include inline images instead of an external link

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Re: MC7455 and ROOTer - Troubleshooting Connection Issues

Post by JimHelms » Sat Jun 16, 2018 9:58 am

While under powering a router/modem can create connection issues, so will lack of a good signal which is most likely the culprit in your case.

Heavily wooded areas are difficult for signals to penetrate. The higher the frequency, the shorter its wave length, the greater its absorption and the more difficult its penetration. On the opposite side, the lower the frequency, the larger the wave length, and the higher its penetration and power--especially over distances.

You will notice this difference in your quality of signal stats between Band 26 (850HMz) and Band 41 (2500MHz).

While Band 41 is always preferred (when attainable), have you tried locking the modem to band 25 (1900MHz)?

Maybe someone can offer more input and/or suggestions, as mine are somewhat limited.

I would make sure to use quality 50 ohm low loss coax cables between the router/enclosure and the antennas.

You may try repositioning (or relocating) one or both antennas, or try a different type of antenna altogether.

In my experience, and as unscientific as it may be, optional results are sometimes obtainable only by trial and error.

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