@terziyski Thanks so much for the assistance! Can you recommend any device (other than a router) that I can buy to replace the switch?

@terziyski The ISP cable runs directly into the network switch (it's my own, not the ISP's), then the routers are connected to the switch. I'm not aware of any device that sits before the network...

@terziyski My switch modem is tplink tl-sg1005d v8, it's one of those plug-and-play devices.

@terziyski So here's what happens when I configure both routers in AP mode (dynamic IP, no DHCP). The former main router (A) claims IP 10.108.165.230, so do all devices connected to it via WIRE. All...

@terziyski if I set them both in AP mode should I disable DHCP on both of them or neither? Also do I assign static IPs to them?

@terziyski The topology can be seen in the picture of the first post. My main router's LAN IP address is 192.168.0.1 and it's DHCP IP pool is 192.168.0.2-192.168.0.254 with a 255.255.255.0 netmask....