/dev/cdc-wdm0 not responding

Hi,

I’ve got a router with the EC25 LTE modem:
Bus 001 Device 003: ID 2c7c:0125 Quectel Wireless Solutions Co., Ltd. EC25 LTE modem

The router is running OpenWrt 19.07.3 r11063-85e04e9f46 which has 4.14.180 linux kernel.

Modem has the following firmware:
root@OpenWrt:~# socat - /dev/ttyUSB2,crnl
ATI
Quectel
EC25
Revision: EC25EFAR06A06M4G
OK

I’ve enabled ppp & qmi mode with the following over ttyUSB2: AT+QCFG="usbnet",0
This makes the device show up as /dev/cdc-wdm0 .
When I try to use uqmi to do anything ie. check for signal strength ( uqmi -d /dev/cdc-wdm0 --get-data-status --get-signal-info ), the device is totally unresponsive.

How can I troubleshoot this?