Hi
I try to connect my 5G WWAN Card.
The Card is detectet with the Ports: eth3 (net), ttyUSB4 (at)
in the log i can see netifd try to set the IP to ttyUSB4 "Command failed: ubus call network interface nitify_proto { ... "ifname": "ttyUSB4" ..} (Unknown error)

with a other card ports: cdc-wdm0 (qmi), ttyUSB0 (ignored), ttyUSB1 (gps), ttyUSB2 (at), ttyUSB3 (at), wwan0 (net)
it work. Is the problem that on the first card the net port is the first and not the last port?
i cant see no other difference as the order?

Please show the output of cat /sys/kernel/debug/usb/devices

T:  Bus=01 Lev=04 Prnt=07 Port=02 Cnt=01 Dev#= 10 Spd=480  MxCh= 0
D:  Ver= 2.10 Cls=ef(misc ) Sub=02 Prot=01 MxPS=64 #Cfgs=  1
P:  Vendor=0e8d ProdID=7126 Rev= 0.01
S:  Manufacturer=Fibocom Wireless Inc.
S:  Product=FM350-GL
C:* #Ifs= 8 Cfg#= 1 Atr=a0 MxPwr=500mA
A:  FirstIf#= 0 IfCount= 2 Cls=e0(wlcon) Sub=01 Prot=03
I:* If#= 0 Alt= 0 #EPs= 1 Cls=02(comm.) Sub=02 Prot=ff Driver=rndis_host
E:  Ad=82(I) Atr=03(Int.) MxPS=  64 Ivl=125us
I:* If#= 1 Alt= 0 #EPs= 2 Cls=0a(data ) Sub=00 Prot=00 Driver=rndis_host
E:  Ad=81(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms
E:  Ad=01(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms
I:* If#= 2 Alt= 0 #EPs= 2 Cls=ff(vend.) Sub=00 Prot=00 Driver=(none)
E:  Ad=83(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms
E:  Ad=02(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms
I:* If#= 3 Alt= 0 #EPs= 2 Cls=ff(vend.) Sub=42 Prot=01 Driver=(none)
E:  Ad=84(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms
E:  Ad=03(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms
I:* If#= 4 Alt= 0 #EPs= 2 Cls=ff(vend.) Sub=00 Prot=00 Driver=option
E:  Ad=85(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms
E:  Ad=04(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms
I:* If#= 5 Alt= 0 #EPs= 2 Cls=ff(vend.) Sub=00 Prot=00 Driver=(none)
E:  Ad=86(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms
E:  Ad=05(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms
I:* If#= 6 Alt= 0 #EPs= 2 Cls=ff(vend.) Sub=00 Prot=00 Driver=(none)
E:  Ad=87(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms
E:  Ad=06(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms
I:* If#= 7 Alt= 0 #EPs= 2 Cls=ff(vend.) Sub=00 Prot=00 Driver=(none)
E:  Ad=88(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms
E:  Ad=07(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms

root@OpenWrt:/# mmcli -m 2
  --------------------------------
  General  |                 path: /org/freedesktop/ModemManager1/Modem/2
           |            device id: XXXXXXXXXXXXXXXXXXXXXX
  --------------------------------
  Hardware |         manufacturer: Fibocom Wireless Inc.
           |                model: FM350-GL
           |    firmware revision: 81600.0000.00.29.21.24
           |            supported: gsm-umts, lte
           |              current: gsm-umts, lte
  --------------------------------
  System   |               device: /sys/devices/platform/soc/11200000.usb/usb1/1-1/1-1.4/1-1.4.4/1-1.4.4.3
           |              physdev: /sys/devices/platform/soc/11200000.usb/usb1/1-1/1-1.4/1-1.4.4/1-1.4.4.3
           |              drivers: rndis_host, option1
           |               plugin: fm350gl
           |         primary port: ttyUSB4
           |                ports: eth3 (net), ttyUSB4 (at)
  --------------------------------
  Numbers  |                  own: XXXXXXXXXXXXXXXX
  --------------------------------
  Status   |       unlock retries: sim-pin (3), sim-puk (10), sim-pin2 (3), sim-puk2 (10)
           |                state: disabled
           |          power state: on
  --------------------------------
  Modes    |            supported: allowed: 3g; preferred: none
           |                       allowed: 4g; preferred: none
           |                       allowed: 3g, 4g; preferred: none
           |                       allowed: 5g; preferred: none
           |                       allowed: 3g, 5g; preferred: none
           |                       allowed: 4g, 5g; preferred: none
           |                       allowed: 3g, 4g, 5g; preferred: none
           |              current: allowed: 3g, 4g, 5g; preferred: none
  --------------------------------
  IP       |            supported: ipv4, ipv6, ipv4v6
  --------------------------------
  3GPP     | packet service state: detached
  --------------------------------
  3GPP EPS | ue mode of operation: csps-2
  --------------------------------
  SIM      |     primary sim path: /org/freedesktop/ModemManager1/SIM/2
  --------------------------------
  Bearer   |                paths: /org/freedesktop/ModemManager1/Bearer/2

the log
the interfacename pppppp is the name i set in lucie for the wwan connecttion

Sun May 12 16:16:24 2024 daemon.notice netifd: pppppp (6690): Command failed: ubus call network.interface notify_proto { "action": 0, "ifname": "ttyUSB4", "link-up": true, "keep": true, "ipaddr": [ { "ipaddr": "xxx.xx.176.128", "mask": "255.255.255.255" } ], "interface": "pppppp" } (Unknown error)
Sun May 12 16:16:24 2024 daemon.notice netifd: pppppp (6690): IPv6 connection setup required in interface pppppp: dhcp
Sun May 12 16:16:24 2024 daemon.notice netifd: pppppp (6690): Command failed: ubus call network.interface notify_proto { "action": 0, "ifname": "ttyUSB4", "link-up": true, "keep": true, "interface": "pppppp" } (Unknown error)
Sun May 12 16:16:24 2024 daemon.notice netifd: pppppp (6857): stopping network

I suggest removing ModemManager and use another connection method described in that thread.

i try to create a custom modemmanger modul and all works except that netifd try to give the wrong networkinterface (ttyUSB4) the ip adress. I need to know how netifd select the interface from modemmanager

if i give the rndis interface the ip manually the connection work so basically it should possible tu use mm