No indication of Konnected board being offline

Thats what I was getting at above:

You might be able to monitor one of the attached devices for activity.

You could also us this to setup a periodic ping check from HE: [Release] Hubitat Ping

You would need to create a rule to alert you if the ping fails.

Those are part of the new HE platform 2.4.0, you must have not have updated yet.