the scenario is as follows:

First I have a cable modem which gives the internet connection. The network is 192.168.0.0/24 and its IP is 192.168.0.1

Second line, I have a router connected to the cable modem. Its "outside" IP is 192.168.0.12. This router creates network 192.168.123.0/24 and its IP there is 192.168.123.254.

My computer is wired to the router with IP 192.168.123.126.

At this point I am able to access both devices web interfaces by their IPs on a browser (192.168.123.254 for the router and 192.168.0.1 for the cable modem).

The problem I have is when I connect to a VPN from the computer. Then I am connected to a second network 10.0.0.0/24 and I get IP 10.0.0.200 (along with 192.168.123.126). I can connect to the router but then I loose connectivity to the cable modem: I cannot acces it through the browser, neither making a ping to it or a tracert.

I have tried to add a new route to the windows routes by typing

route ADD 192.168.0.1 MASK 255.255.255.0 192.168.123.254

but I cannot access it anyway...

Am I missing something on the route adding? Which is the propper way of doing this? Thanks