Error when trying to start Mirroring Thanks for looking at this, and thank you in advance for any answers! 

I am attempting to start a mirroring session, but I am getting an Error 1418, which basically states that the TCP port doesn't exist. However, when I look at the SQL Logs, I am seeing a completely different error. It says that the login does not have CONNECT permissions on the endpoint. 

Here is the problem, I do not know where this Login is coming from. It doesn't exist. It's never existed. It's not the login that I am using when connecting to either the Principal or the Mirror. 

I can't create this login because there is a '$' in it, which again, makes no sense. Any help would be astronomically appreciated! Thank you.
So it seems that the issue was actually related to certificates. Once the certificate was backed up and shared to the mirrored server, everything worked as intended. I just wanted to swing back around and let those who were reaching out to help know where I landed.