Homeplugs / powerline adapters are the answer - click here But look for the kit with two slaves / remote connectors. Plug the one with the pass through socket in next to the main router and the remotes elsewhere in the house. They use mains wiring to connect thus avoiding the need for LAN cables. This kit will clone the main WiFi ssid & password and rebroadcast it from the remotes giving seamless connection throughout the house. You can also plug in your other router / devices to the remotes and use them as extenders if you wanted.
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