If you are using a router as an access point and it's connected to another router through wifi, you cannot use it's wifi anymore. It's been designated for other use. You need to connect you PC directly to the 3rd router.
See example here
- Connect using wire from DSL to Router1 in WAN port.
- Router1 becomes main router, assign it an IP address of 192.168.1.1 (or something like that)
- Enable DHCP on Router1
- Router2 becomes slave router, assign it an IP address of 192.168.1.2 (or something like that)
- Connect Router2 through WiFi to Router1.
- All connections to Router2 needs to be wired.
- All WiFi connections need to be connected to Router1
Should you want to connect your routers with a hard wire, then you have two choices.
Option 1: Chain the Routers to make one big network
- Assign Router1 a static IP address like 192.168.1.1
- Assign Router2 a static IP address in the same subnet as Router1 like 192.168.1.2
- Both of those IPs should be outside of you DHCP range.
- Turn off DHCP on Router2
- Plug Ethernet cable into the LAN port (1 of the 4) in Router1
- Then plug the other end of the Ethernet cable into the LAN port (1 of the 4) into Router2.
- Router1 is you main router. It is the DHPC server, the DNS Server, the gateway, etc.
- Router2 acts as a Switch with Wireless capabilities
Option 2: Chain Routers to make separate 2 Networks
- On Router1
- Assign a Static IP address like 192.168.1.1
- Enable DHCP, scope cannot contain above IP
- On Router2
- Assign a Static IP address, one that is not on the same subnet as Router1 something like 192.168.2.1
- Enable DHCP, scope cannot contain above IP and must be in the same subnet as Router2
- Plug Ethernet cable in LAN port on Router1
- Plug other end of Ethernet cable into WAN port of Router2
- Devices plugged to Router2 can see Devices plugged into Router1, but not the other way around.
- Router2 will obtain it's WAN IP from Router1 and will route traffic from it to Router1.
Hope this helps.