ModemManager - connecting multiple modems simultaneously always fail

[Aleksander Morgado]

Hey,

> Hey guys. I’m trying to connect 3+ modems on my PI, all of these modems are working if I connect them individually, but once I connect all of them together I get at least one that can’t get a connection.
>
> Something always happens on the third modem that makes it stay in a unknown state:
>
>   -------------------------
>   General |           path: /org/freedesktop/ModemManager1/Modem/3
>   -------------------------
>   System  |         device: /sys/devices/platform/soc/3f980000.usb/usb1/1-1/1-1.1/1-1.1.2/1-1.1.2.4/1-1.1.2.4.6
>           |        drivers: qmi_wwan, option
>           |         plugin: generic
>           |   primary port: cdc-wdm2
>           |          ports: cdc-wdm2 (qmi), ttyUSB7 (at), ttyUSB8 (at), wwan2 (net)
>   -------------------------
>   Status  | signal quality: 0% (cached)
>   -------------------------
>   Modes   |      supported: allowed: any; preferred: none
>           |        current: allowed: any; preferred: none
>
> This modem works when I connect it by itself. I also tested different permutations and it seems it’s always the third modem that can’t get a connection, independently of which one I put on first. This is the full log with debug on: https://pastebin.com/L3QWBppt
>
> Any ideas?

Maybe there's too much current drained by the 3 modems when connected?
Are the modems powered through an intermediate USB hub with its own
power? Or are the modems all being powered by the RPi USB ports
directly?

-- 
Aleksander
https://aleksander.es