How to set routes for simultaneous operation of a USB modem in APN and a router on the Internet?

Question

Network routing

Good afternoon! Tell me how to properly configure the network on a Windows 10 PC. It is connected to APN via a 3G USB modem, the PC address in APN is 192.168.1.1/28, there is a connection with other hosts. The PC needs to be given access to the Internet, as soon as I connect the router, then communication with hosts via APN stops. I tried to set static routes with the command
route -p add 192.168.1.3 mask 255.255.255.240 192.168.1.1
but it did not help. I see with the tracert 192.168.1.3 command that the first address 192.168.88.1 is a router.
How to make both APN work (access to the 192.168.1.0/28 network was via a USB modem) and the Internet through a router?

Answer 1

your router subnet is 192.168.88.0/24??
then on the modem interface - disable the gateway and DNS
or add routes like this...
route add 10.41.0.0(APN subnet) mask 255.255.0.0 10.27.0.1(IP that your PC received in the APN subnet)
route add 192.168.1.0 mask 255.255 .255.240 192.168.1.1