MSSQL Mirror Configuration Troubleshooting: Witness server forcibly disconnecting every 100 seconds I recently set up a three servers running MSSQL Server 2016 in a high safety synchronous mirroring configuration.  Right now, everything is working normally.  Any changes made in the principal are replicated on the mirror consistently.

However, both the Principal and the Mirror server constantly have the error:

"Database mirroring connection error 4 'An error occurred while receiving data: '10054(An existing connection was forcibly closed by the remote host.)'.' for 'TCP://WITNESS_SERVER:5022'."

The Witness server also has the exact same error toward both the Principal and the Mirror.  There are no errors between the Principal and Mirror, and there are no other accompanying errors (Handshake rejected, etc...).  Interestingly, these disconnects occur repeatedly exactly 100 seconds apart without cease.  They do not happen at the same time for the Mirror and Principal, and currently are offset by about 12 seconds.  Has anyone run into a similar issue or know exactly what sort of issue can lead to 100 second forced disconnects?
We reported the issue to Microsoft support and got it fixed. I have also tested SP1 CU1 and the database mirroring error messages have disappeared. So I think that all is good.
https://support.microsoft.com/en-us/help/3210699/fix-error-messages-are-logged-if-database-mirroring-is-configured-by-transact-sql-in-sql-server-2016-and-no-database-activity-occurs-for-more-than-90-seconds