How and where do I confirm TCP ports are open when performing mirroring? (Principal, Mirror & Witness) I have a SQL 2017 Principal, Mirror and Witness that I'm trying to set up for high-availability. I've created certificates specifying port 7024 because the customer is running in a Workgroup and not a Domain.  I keep getting the attached error when trying to start mirroring.  I've tried specifying 7024 as the TCP port in the SQL Configuration Manager. Is there something I'm missing?  Does the port for the Mirroring endpoint need to be different from the Principal?  I've tried searching here for the same error but I'm getting mixed information about this.



The error message shown is:


  The server network address "TCP://kb-versiosql1:7024" can not be reached or does not exist. Check the network address name and that the ports for the local and remote endpoints are operational. (Microsoft SQL Server, Error: 1418)
Thanks to everyone who commented!  Your suggestions were all extremely helpful.  I was able to re-trace my steps and did the following:


Made sure certificates were created for both partners, AND Witness authorized using the correct logins and '.cer' files.


Allowed CONNECT permission on login for remote mirroring endpoint.