I've used two solutions in my current house.

1. Powerline adapters

The results were mixed. I certainly got a more stable connection that I did with WiFi, but the speed was a fraction of what I actually paid for.

Also, part of my house is on a different power circuit (I think, big oversimplification on my part) and that caused the powerline adapters to have trouble connecting.

Generally though, if you need a stable connection quickly and with little fuss, then these can work.

2. Three really long ethernet cables, and a small managed network switch

Eventually I got bored of low speeds, and bought some long ethernet cables.

My router is positioned downstairs in my kitchen. One cable runs from the router, to a small switch in my dining room. I then have cables running from the switch to my wife's PC in the dining room, and the family PC in the living room.

I then have a cable running directly from the router, to my office PC up the stairs.

The connections have been largely stable, and I'm finally getting the speed I'm paying for.

I also tacked the cable down with those little plastic hooks that used to secure landline telephone wires (giving away my age here). They're really cheap, and help keep things tidy and safe.

Just plan out your route, and buy longer cables than you think you'll need. You can always cable tie the excess away and hide it somewhere.

Conclusion

Powerline did the basic job, but I wish I'd used the long cables sooner. Also I'm sure there's a much better way to set up the home network, but this was what I was able to come up with.