Large old 5 bedroom house (2 floors) with the SH located in my office downstairs at one end of the house. Very reliable wired connection 200Mbps (now 350) at all times, more or less. Acceptable wifi speeds close to the SH. Useless wifi speeds elsewhere. 2 teenagers constantly complaining about "no wifi, useless wifi". So I bought a more powerful router (Netgear R6400-100UKS AC1750) in the hope it would solve the problems. The result, for me, was a very small improvement in wifi speed in the rest of the house. The improvement was not significant and certainly did not satisfy my children. I sold the router on ebay.
Running cables through the house was not an option for me.
So I set up a network using TP-Link powerline adapters and 4 old routers (BT and Sky) bought on ebay for a few pounds each. The BT and Sky routers are set up as access points in the lounge, tv room and each child's bedroom. We now get around 50/60Mpbs in every room in the house. The network has been running for about 18 months with more or less no problems. No issues with streaming services like Netflix and Amazon Prime or gaming etc. Kids happy.
I'm tempted to buy an Orbi RBK50 or 53 and set up a mesh network but that's a substantial cost without a gauranteed improvement. Let's see what Santa brings.