Hi,
Thank you for posting in Symantec community.
It seems again you have been affected by a known issue.
Too many active connections from the Group Update Provider (GUP) to Symantec Endpoint Protection Manager
Fix ID: 3110944
Symptom: The Group Update Provider (GUP) computer keeps more than 200 connections open to Symantec Endpoint Protection Manager.
Solution: Fixed a callback function that was not properly called before closing
Reference: New fixes and features in Symantec Endpoint Protection 12.1.4
I would recommend to upgrade to the latest version of SEPM i.e. 12.1 RU4a.