09:27 UTC - Monitoring agent on one of the nodes stopped responding then started responding again a few seconds afterwards. We put it on a random network error.
09:39 UTC - Some users start to have issues using their free add-on.
09:40 UTC - We investigate. It turns out that the mongodb process was not really listening to incoming connections anymore.
09:42 UTC - We try to restart the service.
09:46 UTC - We actually reboot the whole VM.
09:47 UTC - The VM is up and running, the mongodb process is cleaning itself up.
09:50 UTC - The mongodb process finishes its cleanup and starts accepting connections again.