I have to build wireless network in а big house. For this I have got four RB951G-2HnD routers ( it is enough for good coverage). The inbound ISP link comes to one of the routers. Other three routers are distributed around the house and there`re no wired connections beetwen them and main router.
I tried different types of setups (wds, mesh, repeaters, bridges) in order to get good working wireless network around the house. But each time I got very small internet speed and big ping on client devices. Is it normal or there are some methods to improove the situation? I can`t provide wired connections beetwen routers.

You will need wires indeed. Are you aware of powerline ethernet adapters?

You will need wires indeed. Are you aware of powerline ethernet adapters?

Yes, I think about it. But there`re a lot of smart house electronic which are already using electric wires as a communication infrastructure and I`m afraid powerline ehternet will not work.

Then get repeaters closer or run wires to them. Wires are always the best.