Configuring SQL Merge replication when using a custom SQL port fails with the error "A network-related or instance-specific error occurred while establishing a connection to SQL Server" (4339077)

Attempting to configure SQL Merge Replication when Active Roles is configured to connect to SQL using a custom port fails with the error:

A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. (provider: Named Pipes Provider. error: 40 - Could not open a connection to SQL Server)

This is due to a limitation in Microsoft SQL. Merge Replication cannot be configured when the connection string contains custom ports.

1. In an elevated command prompt, run cliconfg which will open the 64-bit SQL Server Client Network Utility
2. When the SQL Server Client Network Utility opens, click on the Alias tab, then Add
3. Configure the following:

1. Use the same steps above to configure 64-bit aliases on the SQL hosts so that they have a reference for each other SQL host.
2. Create a 32-bit SQL alias on the SQL hosts for the other SQL hosts using SQL Server Management Studio as per this Microsoft reference.

1. In the Active Roles Configuration Center, on the Administration Service tab, click the Change button to change the SQL database being used
2. Configure Active Roles to use the new SQL alias to connect to SQL, instead of the custom port
3. Repeat these steps on all Active Roles Administration Service nodes.

After these steps have been performed on all Active Roles Administration Service nodes, promote and add subscribers in the Active Roles Console as per normal.