One other thing I didn’t know: you can’t transparently roam between wifi networks, not even access points.
My parents got a big house with thick walls, so I had to install 2 extra CPL Access Points on top of their ADSL box to spread the signal everywhere. But tablets and phones won’t switch from one AP to the other when moving from room to room. There must first be an error from their current AP, then they’ll look for a better one. Stationary PCs are fine, but this sucks for tablets, and is majorly user-unfriendly.
And this happens whether all AP have the same network name + password + band, different ones, no password… There’s an app in the Android PlayStore that proactively re-scans wifi networks periodically, but really it should be built-in, especially for registered networks.