@Alexandre. It shows as connected to gym at 2.4/5 and gym shows connected to office (the master) at 2.4/5. So that doesn't seem to be the issue. I'm confident it can communicate at 5ghz because I've...

We have 8 Decos, mostly v2, three v4. All run in AP mode, and this is in an Active Directory environment. One will only allow connections to the guest (2.4g) network. The guest network is connected...