Here's a doozie I've been dealing with. I have had two WRT54GS2 routers hard linked for last 5 years with no problems. A kid wanted to set up a Minecraft server and so I went to access my router config with no luck. First time this has ever happened. But, it only happens when connected to the internet.
I've already reset both routers multiple times and have re-updated firmware. I checked ipconfig and this is where it got interesting. When the routers are disconnected from internet default gateway on my desktop into Router A is 192.168.1.1 and my desktop into Router B is 192.168.1.2 which is what I set them to. However, when connected to the internet the default gateway is midco.net's 18.104.22.168. For reference below is ipconfig. Thanks
To me , for whatever reason, it sounds like they automatically drop into 'passthrough' mode (i.e. turn off the 'router' and instead are dumb switches) when connected to your service. FYI, it is normal that they pass along the default gateway as the service, as they are receiving the DHCP info that 22.214.171.124 (the Router Modem from mico.net) is the actual gateway service. May I ask WHY you have two routers (or more) on this network? That isn't the normal / best solution for a network, and infact unless one router is disabled (pass through enabled) usually causes interfernce, as both act as the 'one in charge' and constantly fight over it.
The reason for two routers is the building layout, internet access is needed throughout but not available with one router. Haven't dealt with any conflict problems with separate IPs for each router. I do know that the isp sends their ip as gateway, but linksys router gateway should also appear in ipconfig of desktop connected to router A. But for what it's worth, I did check router A to ensure the modem in was connected to proper WAN port. I had told the kid how to power cycle the modem & router and he had the copier plugged into WAN. Needless to say they are properly labeled now.