by having both routers set to DHCP assigning the same IP address range. Set the second router to assign different IP range. May also have to change the gateway on the second router to somewhere in that range. Make sure the second router gets an IP address from the first router if piggybacked from it.
Ok, I have what I think is a unique problem. So here is the setup. I have a older Linksys E2500 WIFI router that I wanted to set up in my bedroom. I have another Linksys EA6300 that I have setup in the office. The modem (Time Warner cable) is located in the office and is connected to my Apple computer and to the 6300. So I also have a network of Actiontec Coax Network Adapters that are also connected to the modem, tv in living room, bedroom and bonus room. By the way, they are great, basically gives your smart tv a direct internet connection, so no slow WIFI. So what I though I could do was setup the 2500 in the office, then unplug it and move it to the bedroom connected to the Actiontec by a wired connection. the 2500 router shows that it is receiving internet signal, the PS4 works, and so does the Apple TV. But when I connect to the router my iPad and phone can not connect to the internet. So I'm not sure if I am over reaching and this connection isn't possible or something is off. When I move the 2500 back into the office and plug it up, it works fine. So my question is why doesn't it work off the coax adapter if Internet signal is coming through to everything else?