ModemManager - connecting multiple modems simultaneously always fail

[Lucas Pelegrino]

Hello.

Yes, the modems are powered through an intermediate USB hub with its own
power.

Is there a way to confirm if it's a power issue?

Em dom., 26 de set. de 2021 às 05:19, Aleksander Morgado <
aleksander at aleksander.es> escreveu:

> 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
>
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