Hello, we have an nROK 1031 pc with an EM05-G modem pre installed (firmaware EM05EFAR06A05M4G)
We have currently installed Ubuntu server 22.04 with kernel 5.15.0-73-generic (but we have tried other OS), with a simple netplan config (NetworkManager + ModemManager) who is working fine if we launch ModemManager after boot, but not during it.
In journal we can see a lot of USB disconnections during the boot phase blocking the ModemManager operations:
Jun 09 11:59:01 goal kernel: usb 1-3: USB disconnect, device number 6
Jun 09 11:59:01 goal kernel: option1 ttyUSB0: GSM modem (1-port) converter now disconnected from ttyUSB0
Jun 09 11:59:01 goal kernel: option1 ttyUSB1: GSM modem (1-port) converter now disconnected from ttyUSB1
Jun 09 11:59:01 goal kernel: option1 ttyUSB2: GSM modem (1-port) converter now disconnected from ttyUSB2
Jun 09 11:59:01 goal kernel: option1 ttyUSB3: GSM modem (1-port) converter now disconnected from ttyUSB3
Jun 09 11:59:01 goal kernel: cdc_mbim 1-3:1.4 wwan0: unregister 'cdc_mbim' usb-0000:00:14.0-3, CDC MBIM
Jun 09 11:59:02 goal kernel: usb 1-3: new high-speed USB device number 7 using xhci_hcd
Jun 09 11:59:02 goal kernel: usb 1-3: New USB device found, idVendor=2c7c, idProduct=0125, bcdDevice= 3.18
Jun 09 11:59:02 goal kernel: usb 1-3: New USB device strings: Mfr=1, Product=2, SerialNumber=0
Jun 09 11:59:02 goal kernel: usb 1-3: Product: LTE Module
Jun 09 11:59:02 goal kernel: usb 1-3: Manufacturer: Quectel Incorporated
Jun 09 11:59:02 goal kernel: usb 1-3: GSM modem (1-port) converter now attached to ttyUSB0
Jun 09 11:59:02 goal kernel: usb 1-3: GSM modem (1-port) converter now attached to ttyUSB1
Jun 09 11:59:02 goal kernel: usb 1-3: GSM modem (1-port) converter now attached to ttyUSB2
Jun 09 11:59:02 goal kernel: usb 1-3: GSM modem (1-port) converter now attached to ttyUSB3
Jun 09 11:59:02 goal kernel: cdc_mbim 1-3:1.4: cdc-wdm0: USB WDM device
Jun 09 11:59:02 goal kernel: cdc_mbim 1-3:1.4 wwan0: register 'cdc_mbim' at usb-0000:00:14.0-3, CDC MBIM, 7a:39:2f:a5:a2:0f
Jun 09 11:59:06 goal kernel: usb 1-3: USB disconnect, device number 7
Jun 09 11:59:06 goal kernel: option1 ttyUSB0: GSM modem (1-port) converter now disconnected from ttyUSB0
Jun 09 11:59:06 goal kernel: option1 ttyUSB1: GSM modem (1-port) converter now disconnected from ttyUSB1
Jun 09 11:59:06 goal kernel: option1 ttyUSB2: GSM modem (1-port) converter now disconnected from ttyUSB2
Jun 09 11:59:06 goal kernel: option1 ttyUSB3: GSM modem (1-port) converter now disconnected from ttyUSB3
Jun 09 11:59:06 goal kernel: cdc_mbim 1-3:1.4 wwan0: unregister 'cdc_mbim' usb-0000:00:14.0-3, CDC MBIM
Jun 09 11:59:07 goal kernel: usb 1-3: new high-speed USB device number 8 using xhci_hcd
Jun 09 11:59:07 goal kernel: usb 1-3: New USB device found, idVendor=2c7c, idProduct=0125, bcdDevice= 3.18
Jun 09 11:59:07 goal kernel: usb 1-3: New USB device strings: Mfr=1, Product=2, SerialNumber=0
Jun 09 11:59:07 goal kernel: usb 1-3: Product: LTE Module
Jun 09 11:59:07 goal kernel: usb 1-3: Manufacturer: Quectel Incorporated
Jun 09 11:59:07 goal kernel: usb 1-3: GSM modem (1-port) converter now attached to ttyUSB0
Jun 09 11:59:07 goal kernel: usb 1-3: GSM modem (1-port) converter now attached to ttyUSB1
Jun 09 11:59:07 goal kernel: usb 1-3: GSM modem (1-port) converter now attached to ttyUSB2
Jun 09 11:59:07 goal kernel: usb 1-3: GSM modem (1-port) converter now attached to ttyUSB3
Jun 09 11:59:07 goal kernel: cdc_mbim 1-3:1.4: cdc-wdm0: USB WDM device
Jun 09 11:59:07 goal kernel: cdc_mbim 1-3:1.4 wwan0: register 'cdc_mbim' at usb-0000:00:14.0-3, CDC MBIM, 7a:39:2f:a5:a2:0f
Jun 09 11:59:12 goal kernel: usb 1-3: USB disconnect, device number 8
Jun 09 11:59:12 goal kernel: option1 ttyUSB0: GSM modem (1-port) converter now disconnected from ttyUSB0
Jun 09 11:59:12 goal kernel: option1 ttyUSB1: GSM modem (1-port) converter now disconnected from ttyUSB1
Jun 09 11:59:12 goal kernel: option1 ttyUSB2: GSM modem (1-port) converter now disconnected from ttyUSB2
Jun 09 11:59:12 goal kernel: option1 ttyUSB3: GSM modem (1-port) converter now disconnected from ttyUSB3
Jun 09 11:59:12 goal kernel: cdc_mbim 1-3:1.4 wwan0: unregister 'cdc_mbim' usb-0000:00:14.0-3, CDC MBIM
Jun 09 11:59:13 goal kernel: usb 1-3: new high-speed USB device number 9 using xhci_hcd
Jun 09 11:59:13 goal kernel: usb 1-3: New USB device found, idVendor=2c7c, idProduct=0125, bcdDevice= 3.18
Jun 09 11:59:13 goal kernel: usb 1-3: New USB device strings: Mfr=1, Product=2, SerialNumber=0
Jun 09 11:59:13 goal kernel: usb 1-3: Product: LTE Module
Jun 09 11:59:13 goal kernel: usb 1-3: Manufacturer: Quectel Incorporated
Jun 09 11:59:13 goal kernel: usb 1-3: GSM modem (1-port) converter now attached to ttyUSB0
Jun 09 11:59:13 goal kernel: usb 1-3: GSM modem (1-port) converter now attached to ttyUSB1
Jun 09 11:59:13 goal kernel: usb 1-3: GSM modem (1-port) converter now attached to ttyUSB2
Jun 09 11:59:13 goal kernel: usb 1-3: GSM modem (1-port) converter now attached to ttyUSB3
Jun 09 11:59:13 goal kernel: cdc_mbim 1-3:1.4: cdc-wdm0: USB WDM device
Jun 09 11:59:13 goal kernel: cdc_mbim 1-3:1.4 wwan0: register 'cdc_mbim' at usb-0000:00:14.0-3, CDC MBIM, 7a:39:2f:a5:a2:0f
Jun 09 11:59:18 goal kernel: usb 1-3: USB disconnect, device number 9
Jun 09 11:59:18 goal kernel: option1 ttyUSB0: GSM modem (1-port) converter now disconnected from ttyUSB0
Jun 09 11:59:18 goal kernel: option1 ttyUSB1: GSM modem (1-port) converter now disconnected from ttyUSB1
Jun 09 11:59:18 goal kernel: option1 ttyUSB2: GSM modem (1-port) converter now disconnected from ttyUSB2
Jun 09 11:59:18 goal kernel: option1 ttyUSB3: GSM modem (1-port) converter now disconnected from ttyUSB3
Jun 09 11:59:18 goal kernel: cdc_mbim 1-3:1.4 wwan0: unregister 'cdc_mbim' usb-0000:00:14.0-3, CDC MBIM
Jun 09 11:59:18 goal kernel: usb 1-3: new high-speed USB device number 10 using xhci_hcd
Jun 09 11:59:19 goal kernel: usb 1-3: New USB device found, idVendor=2c7c, idProduct=0125, bcdDevice= 3.18
Jun 09 11:59:19 goal kernel: usb 1-3: New USB device strings: Mfr=1, Product=2, SerialNumber=0
Jun 09 11:59:19 goal kernel: usb 1-3: Product: LTE Module
Jun 09 11:59:19 goal kernel: usb 1-3: Manufacturer: Quectel Incorporated
Jun 09 11:59:19 goal kernel: usb 1-3: GSM modem (1-port) converter now attached to ttyUSB0
Jun 09 11:59:19 goal kernel: usb 1-3: GSM modem (1-port) converter now attached to ttyUSB1
Jun 09 11:59:19 goal kernel: usb 1-3: GSM modem (1-port) converter now attached to ttyUSB2
Jun 09 11:59:19 goal kernel: usb 1-3: GSM modem (1-port) converter now attached to ttyUSB3
If we restart ModemManager after boot or if we simply trigger udev modem it start without problems.
Thanks for your help