Agent Troubleshooting Tool reports endpointcentral-agent1.manageengine.eu unauthorised

Agent Troubleshooting Tool reports endpointcentral-agent1.manageengine.eu unauthorised

So, I'm looking at a couple of problems.

The two issues are:
1. The self serve icon not appearing (running the tray icon exe brings it back, not sure if that sticks)
2. Machines seem to have re-registered themselves, but not completely. So I've got one entry that is offline, and a new entry, that's 'green' but does not scan.

In the process of this I noticed I had the first issue on my machine, so I ran the troubleshooter, and it's telling me that :
https://endpointcentral-agent1.manageengine.eu:443  
The remote server returned an error: (401) Unauthorized.

Connecting manually via browser.. I get endpointcentral-agent1.manageengine.eu redirected you too many times.

Any thoughts?