Ok lets start over here with some real troubleshooting. I read through the thread and things did not really go anywhere thus far.
The first thing to establish is if the hub is actually locking up or is it getting booted off the network and not reconnecting.
For sure try the diagnostic tool next time the hub is offline.
It would be good if you can try and ping the hub when it goes down.
And then once you get it online again check the logs, and see if there is any log history while it was offline or is there a huge gap in the logs?
I think I would like the following info (hand picked from my read first post):
