You upgrade using the MWG manager with an update proxy configured. When you click
Update appliance software, you see the message
Update finished almost immediately.
The file
/opt/mwg/log/update/sysconfd.update.log contains the following error message:
Trying Proxy Server: <proxy ip>:<proxy port>
Proxy not reachable, skip update and switch to next configured proxy, if available
Update failed!
None of the Proxy servers are reachable for repository updates. Update Failed.
Even though the proxy itself might be functioning normally, no TCP connection tries to the proxy are visible on a TCP dump during this time.