Pls help me find the best network setup - eviltoast

So my house has thick brick walls and an L shape.

The fiber cable comes from the attic at one of the ends of the L shape home. There is a wifi 6 isp provided router. The previous solution was a mesh nodes next to the router and another mesh node at the other and of the L shape home where my TV is. The isp provided router wasn’t set to wifi, only the 2 mesh nodes. This solution started dying and the network wasn’t even there in the middle of the L shape.

Now I’m thinking of buying a 3 pack mesh, but there might be a better solution for this.

Can you help me find the best solution?

I have 1gbit internet and the cable comes down at that end because my PC is there, so it has wired connection.