Modify mirroring_partner_instance name in sys.database_mirroring - c++

Question

I have an issue with correctly failing over to the mirror database. When I am connected to the principal database (dbx) (mirroring is enabled and set up) and I fail over the principal database (shutting down SQL Server to simulate a crash), I can no longer send queries without a failure. This is expected since the previous connection is now lost.
I would like to simply close out my connections and handles and re-establish a new connection, using the same connection string, and re-connect to the mirror database (dby, which is now the principal database).
My connection string is as follows:
Driver={SQL Native Client};Server=dbx;Failover_Partner=dby;Database=db;Uid=uid;Pwd=pwd;Network=DBMSSOCN;
From doing research, I have learned that the Failover_Partner parameter in the connection is almost worthless. It is only used when the principal server is down and a new connection is being made for the first time. For some reason, the Failover_Partner is overwritten internally when a connection is established to the principal and the mirroring_partner_instance found in the sys.database_mirroring table is used instead. So when I specify the Failover_Partner to be dby, after I establish a connection, I query for what it thinks the failover partner is, and it returns the INSTANCE name of the failover partner and not the DNS name (dby).
Here is the issue, I cannot use the INSTANCE name as the failover partner. I am required to use the DNS name as the failover partner.
So my question(s) is/are this:
Is there a way to modify the sys.database_mirroring entry and change the mirroring_partner_instance?
Where does this field get its value from?
Is there any other way to force SQL Server to use the DNS name and NOT the INSTANCE name?

Answer 1

I found the answer to this question in case anyone has the same or a similar issue.
I had to modify the ##SERVERNAME property in SQL. It was internally set to the computer WIN-... instance name and I was able to drop it and add the server name I wanted with the following commands:
Get the current server name (WIN_NAME)
SELECT ##SERVERNAME
Drop the WIN-NAME
SP_DropServer 'WIN_NAME'
GO
SP_AddServer 'SERVER_NAME',local
GO
Restart SQL Server to see the changes take effect.