[HELP] Kura 5.5.0 recognises board as MODEM (1-1.1) instead of RNDIS device (usb0) (as previously on Kura 5.3.0)

[alexcorvis84]

Hi,

I have a device running Kura 5.3.0. This device is composed by a RPi4 + 4G Board for communications connected via USB port.

In Kura 5.3.0 board was recognized as usb0 (RNDIS) device, and it worked as expected, being easy to configure and get a successful connection.

Now, I've updated this device to latest Kura 5.5.0, but now the comms board is recognised as MODEM (instead as a RNDIS device).

Despite setting it up as a MODEM and getting it to connect, it disconnects after a short time and is unable to maintain the connection because it is unable to reset the communications module (seems it's not supported by the logs).

Therefore, as I need this device to have a permanent connection, I would like Kura to recognise it only as RNDIS as it did in version 5.3.0 (where it worked perfectly).

What can I do? Is there any way to force the the OS/Kura to detect it as a RNDIS device and not as a MODEM?

Many thanks in advance.

PS: as far as I know in version 5.3.0 comms where managed by the OS and in Kura 5.5.0 (generic arm32) now comms are managed by NetworkManager, right? which seems is not managing properly the board for this device in my case.

[MMaiero]

Hello,
sorry for the late answer.

Do you have any reference to the board you are using and logs that can be shared?

As you said in your last sentence, it is correct that prior to the Kura 5.3.0 the Kura profiles were using only the Kura networking.
From Kura 5.3.0 we have started rolling out new profiles that use network manager. Currently in Kura 5.5.0 all the profiles only use the network manager interaction.

The problem, as you stated, may be related to the fact that network manager is not able to control that device. Are there any meaningful logs for network manager / modem manager that you can share?

Best regards

[alexcorvis84]

Do you have any log from ModemMnager and NetworkManager when the issue you encountered happens?

Unfortunately, I don't think we can "enforce" anything on Kura now that we are not the network managers but instead relying on another service to do the job.

Hi @MMaiero,

Thanks for your comment. As I was looking at the logs, I thought that maybe ModemManager & NetworkManager were scrambling to take control of the communications board. So I tried to disable the ModemManager service (as I didn't want to be recognized as MODEM) and voilà! Now Kura recognizes the board as previously, usb0 (ethernet RNDIS) device.

So many thanks for your support, as it helped me to think about a fix! Now it's working as expected :)

[mattdibi]

Hi there @alexcorvis84,

happy you found a fix.

Just FYI: disabling ModemManager means that, in case you want to handle other modem devices (which probably isn't your case but I'll put it here for documentation purpose), Kura will fail to do so. The "more correct way" to handle this would probably be to add specific udev rules for your device so that ModemManager ignores it.

A quick google search brought me to: https://askubuntu.com/questions/1162279/how-to-tell-modemmanager-to-ignore-some-or-all-of-tttyusb but digging into MM documentation you might find more info.

Also keep in mind that NetworkManager uses ModemManager under the hood to handle modem devices. Therefore there shouldn't be a conflict between them. It's just ModemManager that probably doesn't know how to handle your modem correctly.

[alexcorvis84]

Thanks for your comments. I'm aware of those effects disabling ModemManager, but as you stated, it's not my case, as I don´t want to let it take control of the board being recognized as Modem. At the moment I'll stick to disabling the service as (for me) everything is working as expected, but for sure I'll check your advice and look for a 'softer and cleaner' option that let ModemManager ignore the board as Modem.

Thanks a lot!

[alexcorvis84]

Just FYI: I've just tried it.

Re-enabled ModemManager service and added the following udev rule and it's working! Comms board is recognized as USB0 (ethernet) and not as Modem (ModemManager ignores it). Thank you so much for the suggestion! ;-)

ATTRS{idVendor}=="1e0e" ATTRS{idProduct}=="9011", ENV{ID_MM_DEVICE_IGNORE}="1"

[mattdibi]

Closing this as answered. @alexcorvis84 feel free to reopen this may the need arise.

Thanks for your contribution! :)