Brick and concrete wall is a potential issue. Can you add a repeater device (mains powered outlet) in between the two? An even a simple mains powered outlet (see this post for examples) would help.
If there’s no response at all, then it could be one of 3 things:
- The pairing didn’t happen properly (excluding and repairing should solve that)
- The switch has lost the connection, simply cycling the mains to the switch should fix that
- The Mesh is too weak, you need a repeater.