Between ORION and AlertCentral exists bidirectional connection (so ORION can notify AlertCentral when new alerts are triggered).
It looks like AlertCentral can access ORION (it uses port 17778 for communication), but ORION unable to access AlertCentral (ORION uses https connection on 443 port)
As general rule we recommend to check firewalls.
Also to now more details about what exactly causing exception, log bundle would help (Instructions for collecting Alert Central Logs)
But, if I'm right and it's ORION side problem, then this guys can tell you more about your question (Network Performance Monitor).
Hi, we need Orion logs as well and need to know which Orion version do you use. Please attach here.
It still continues as a problem.
Could you attach logs ?