I doubt that this can be happening on every system.
I suspect that the VPS update process has some timing mechanism for contacting each server, if it does not connect successfully then it moves on to the next server but would run out of servers without success. It seems to me that in a "resource hogging" situation this would most likely affect older, less powerful systems (as was the case in the system used for testing).
I did not report this when it happened on my old system. I wonder how many users, when this might only happen once a month for a day or two at most, would bother to report it.
If you think about it, this user reports no problems in a manual update. Indeed quite a few folks have reported problems with automatic updates, but they can get manual updates. So their systems are perfectly capable of performing the update function, it is nothing wrong with their connections, firewall etc. It is just that something is preventing the avast update process from working properly at system startup.
You (Tech), have often recommended the delayed option for updating, I think in most cases that works for folks by getting the avast update away from all the congestion at startup. I just think that this Windows update issue is a more extreme case of startup congestion.
