On openSUSE (Leap 15.3) i have the routing table:
0.0.0.0 AAA.BBB.145.1 0.0.0.0 UG 0 0 0 br0 AAA.BBB.0.0 0.0.0.0 255.255.0.0 U 0 0 0 br0 192.168.178.0 192.168.178.1 255.255.255.0 UG 0 0 0 eth1
AAA.BBB.145.1 is the default Gateway (outside) 192.168.178.0 ist the internal network via eth1
I can access the outer network through default gateway. I can directly access the second (internal) network, eg 192.168.178.11
But i can´t access it with service, for example with firefox or wget because then the system is trying to get to the host 192.168.178.11 via the external Gateway AAA.BBB.145.1 which of course doesnt know anything about my internal network.
I though i could advise Linux to route all traffic to internal network 192.168.178.0 via 192.168.178.1 but Linux seems not to recognize my wish so i suppose that i have configured the dedicated route over eth1 wrong?