Hopefully, the sketch I've done (below) will be worth 1000 words.

I can successfully have a mesh with the 5 devices if they are all in the house.

I want to take it over the thick wall, to the garage, via the power cord (same line). That's why I got the two P9's.

What I've done:

Have mesh with 3x M5.

Expanded one more node with 1x P9, connected to the plug that goes to the garage.

I went to the garage and tried to add the second P9, by plugging it into the same line as the other P9. No success.

I came back, added it to the mesh, now the total is 5 on the mesh, and took it then to the garage, expecting that now that is configured, would connect over the line.

Is this supposed to work or not? What should I do then?

Thanks!