Why a mesh node should not always go in the weakest room
Mesh placement works best when the node can hear the main router and still cover the weak area. Here is the simple version.
A mesh node needs two jobs: receive a decent signal from the main router and extend coverage toward the weak area. If you place it directly in the worst room, it may be too far away to get a good backhaul connection.
That is why the better first guess is often the hallway, landing, or midpoint between the router and the weak room.
The midpoint rule
If the room is red but the hallway is yellow or green, try the mesh node in the hallway first. Then scan again from the room that used to fail.
The goal is not to maximize the signal at the mesh node alone. The goal is to improve the places where people actually use the network.
Compare before and after
A useful comparison should look at average quality, latency, weak spot count, and the worst measured area. If the weak room improves but latency gets worse everywhere else, the placement may still need work.
SignalNest treats before-and-after comparison as part of the core loop because Wi-Fi placement is physical. You move something, test again, and keep the change only if the experience improves.