Hub Firmware Release Notes - 19.17

New hubs will receive all updates within the first several minutes of bring the hub online for the first time. If the hub went offline sometime after that I would suggest that you open a ticket with support (especially if it happens again). There is one issue with symptoms similar to that (which can cover an umbrella of issues) for which a hotfix should be released on Monday. Emails are going out for that soon if you haven’t gotten one already. Hub Firmware Release Notes - 19.19

An offline notification would also occur if your internet connectivity was disrupted in the middle of the night. This does seem to occur on occation depending on the service provider. Often, a notification on my phone of my hub being offline is the first indication I get that my internet is out.