EM7565, intermittent modem failure

I have an EM7565 attached to Asrock IMB-V200M motherboard running Ubuntu 22.04. Carrier is Twilio and we run latest generic Sierra Wireless firmware on the modem. Intermittently we see a modem failure. This is most common when booting the system after power has been off for more than an hour. We’ve seen this happen on four systems systems so far.

Syslog starts out happy with lots of initialization steps culminating in

May 10 13:21:20 c4-0010 NetworkManager[1410]: <info>  [1683724880.9936] device (cdc-wdm0): Activation: successful, device activated.
May 10 13:21:20 c4-0010 NetworkManager[1410]: <info>  [1683724880.9943] manager: NetworkManager state is now CONNECTED_GLOBAL`

Then the modem goes unresponsive

May 10 13:27:00 c4-0010 ModemManager[861]: <warn>  [modem0/bearer1] reloading stats failed: QMI operation failed: Transaction timed out
May 10 13:27:30 c4-0010 ModemManager[861]: <error> [modem0] port cdc-wdm0 timed out 10 consecutive times, marking modem as invalid```
May 10 13:27:30 c4-0010 NetworkManager[1410]: <warn>  [1683725250.9144] modem-broadband[cdc-wdm0]: failed to disconnect modem: GDBus.Error:org.freedesktop.DBus.Error.UnknownMethod: Object does not exist at path “/org/freedesktop/ModemManager1/Modem/0”

At this point the modem still shows up in lsusb but mmcli -L returns No modems were found. The modem device itself (typically /dev/cdc-wdm0) still exists but I’ve not found any sort of reset command to bring things back. Best we can do is power cycle.

You might attach the module to other host platform to see if your ubuntu has problem