I have an old unused Zyxel VMG1312-B30B router and I am trying to use it as switch in home network to extend it to the attic.
Since it has 4 RJ45 ports, I want to use 1 port as incoming from main home router and remaining 3 are enough at the moment.
I am developer and not network specialist though I am aware of difference between router and switch and basic configuration.
I have read tons of howtos on the web (for example 1, 2, 3) and made lot of attempts. To configure old router as switch, I reset it to factory settings, connect it to standalone notebook, enter admin interface on 10.0.0.138 and do configuration changes: disabling DHCP, Wifi, firewall and changing IP address to 192.168.1.4 (main network is 192.168.1.0 with subnet mask 255.255.255.0 and I verified the IP address is not used; alternatively I narrowed the DHCP range on main router from 192.168.1.2-192.168.1.254 to 192.168.1.2-192.168.1.253 and assigned IP 192.168.1.254 to Zyxel).
After IP address change, the router admin interface (naturally) stops communication on 10.0.0.138 but does not start communication on new 192.168.1.4 address.
However if new address is 10.-like, say 10.0.0.137, the admin interface works.
Is there some possibility that router whose factory local IP address is class A is not reconfigurable to class C IP address? Or is it likely the hardware or firmware problem? What could I do to better diagnostic what’s happening here?
