Upgrade To 2020.4.3 With Clustered SQL Fails With Generic Networking Error : 70

During the upgrade to 2020.4.3 with clustered SQL, how to resolve when it fails with generic Networking error: -70 ?

Issue Description: Whilst upgrading to 2020.4.3, with a clustered SQL environment the following error message pops-up:

System.Exception: Error:70, Message: Am error has occurred while installing the database. A network-related or instance-specific error occurred while establishing a connection to SQL Server.

Root Cause: This is happening if in the SQL connection string, IP address of SQL is being used and if SQL is in a clustered environment. With this scenario, Identity does not know how to reach to SQL and write the new tables.

Resolution: Modify the SQL connection string to be: "".
This would be the way Identity Server is able to identify the right SQL instance and do the upgrade properly.

Note: Individual IP or host name will get in to failure of the upgrade if database is in clustered environment.