Try Powerline. This €40 device will turn your electrical sockets into an 100-500 mbps Ethernet cable. Simple and efficient. Just check if sockets you want to connect are on the same circuit breaker. If yes, chances are really high it would work very well.

I’ve connected a switch and a second access point with mine.

Also I think they work best if there fewer of them on the same circuit. But not sure. Check first.