@David-TP 

Devices that took too long to reconnect: 

1) Samsung S22; this is the only device with the DECO administration app and is the device from which the reboot was iniitiated.  It is identified as a priority device on the main network and preferred 5GHz band.  After the reboot, the device timed out reconnecting after 5 minutes waiting for the network restart, and about another 3 minutes later the app established a connection with the Decos via mobility data network and through internet.  That was first inidication the network had successfully rebooted.

2) Another Samsung S21FE, also tagged priority client on the main network

3) Dell laptop / Windows 11

Devices that had re-established their connection to the network before the priority devices:  Amazon Alexa smart speakers on the main network, several WiFi enabled smart wall switches on the IOT network, and the only 2 guest phones (Apple) on the guest network.  The guest network is not normally enabled; only when I have guests.  It is currently disabled.  Guest devices and low priority IOTs should be the last to reconnect.  

The SSID's are the same on both 2.4GHz and 5GHz for each network type.  Are you suggesting the SSID's should be different for each band?  Most devices that are capable of connecting on either band are configured in the DECO app with a preferred band, and some by location to a preferred Deco node if the device location is fixed and not expected to move around.

David, what's happening here?  Everything seems connected to the main Deco, and all clients connected by wifi to the satellite decos appear as wired connections on the main deco.  This kind of behavior is what initiates necessity of reboots.