I've tested three different modems based on MDM9205 from three different vendors (Quectel, Fibocom, SIMCom). In all cases modem is incapable to provide working IP connectivity to the linux host. PDP context is activated, IP is assigned by network (pingable from AT commands). At the same time USB ECM network interface on linux host also got IP address from DHCP server on the modem.
However the internal modem IP routing between USB and NW stack is not set at all resulting in no internet connectivity to the host. This is only observed on MDM9205. Modems based on MDM9207 works fine...
Any comments on this issue?