ppp as a network switch

I have two devices which uses petalinux as OS. They are custom devices to use on some projects. Their purpose is to act as routers with cabled connection (not ethernet). Devices are connected with cable and with special protocol. So they can not use ethernet interface. I need them to act as a switch. Devices have WEB GUI to configure them. Also they listen some udp sockets and process data. But I also want to transmit all Ethernet packets to other device. So far I tried this : Device 1 IP : 10.0.0.4/24 IP forwarding enable Route 192.168.0.0 via ppp0 Device 2 IP : 192.168.0.5 IP Forwarding enable Route 10.0.0.0 via ppp0 This way devices have a connection and i can transmit packets to other side. But I can not use other IP domains. Both devices need to act as a switch. When I am connected to Device 1's network, I need to access Device 2's WEB GUI. I could not figure out what kind a ip route I should use. What could be the solution?