Mesh Networking for Home - 1 or 2 needed?

[dave343]

My condo walls really kill wifi with the plaster walls and metal honeycomb mesh that’s inside. I’m looking to extend my coverage and purchase some of the mesh network wifi gear but I’m curious to know how many I actually need. My first question would be if these mesh nodes can act as both a client and then AP, or if I’ll need at least 2, and 2nd will one of those mesh devices be required to be plugged into the ISP wifi router. Thx