Sometimes it is necessary to have a second router in your large house. To use a common router as second access-point you have change its settings. The first router is the captain of the network. The second router only access-point.
If the address lines are different, there's not much of a problem. Just connect the second router and off you go: 192.168.x.x.
If router 1 is on 192.168.1.x giving addresses and router 2 is on 192.168.2.x, it all works fine.
But if both routers are on 192.168.1.x, the first router will block the second router. Turn the router function of the second router off and make it a dumb access-point.
This is the way to do that:
Just use the first router as you always did. If it already works, don't change that.
Connect the second router temporarily with a computer with a normal Ethernet cable. Connect it at a Ethernet port and not at the WAN port. Start the router login screen in your browser. Usually at 192.168.1.1. of 192.168.2.1
In this configuration screen you can give your second router a fixed IP address that is out of the range of the DHCP server of the first router. E.G: 192.168.1.150
Turn off the DHCP server in this second router. Make sure the second router is using another channel than your first router. Now your almost done. Close your browser and disconnect the second router from your PC or laptop.
Now connect router one with an Ethernet cable in Ethernet port 1 and connect this cable to Ethernet port 1 on the second router. DON'T USE THE WAN port!
Router 2 is now a dumb access-point for router 1.
You may use this at work if you need more access-point at your desktop, or want to use WIFI where it is not available.