Below is my current setup for home network, but I've been having a fair number of problems with it. The bottom ethernet connection goes to a switch with a few more ethernet devices, and the repeater has a couple of ethernet connections off it too. 

Basically during the weekend, evenings there tend to be a LOT more wifi devices connected (kids + all their friends, etc)  and sometimes things don't run too smoothly. I think most of the issues are wifi related as ethernet devices rarely have issues. 

I also have it setup so that the "standard" wifi profile (that the kids and all their friends end up connected to by default)  blocks late night wifi access but SWMBO doesn't want to turn off MAC randomisation on her phones\tablet and so sometimes the fritzbox seems to think her devices are new devices and blocks them late night. 

I think part of the problem might also be that the 2 devices below are at opposite ends of the house and sometimes wifi devices roaming\switching between them isn't all that smooth? 

Any recommendations for low setup\friction mesh replacements for these devices? Or just one router that I can put in the middle of the house with very good coverage? It is unfortunately a big long house so a bit tricky to cover fully with a single device.  I have not kept up with recent IEEE wifi standards so not sure which I should be looking at.