When SQL Server Browser is not started , and a SQL Server connection attempt is made remotely using the named instance an error 26 message appears. A network related or instance-specific error occurred Error 26 – Error Locating Server/Instance.
The connection attempt finds the server – SERVER1 – but cannot map the instance request to the SQL service running on the server.
The Error 26 message appears in a number of different circumstances. Read SQL Server Error 26 troubleshooting checklist for a list of different causes of Error 26
The root cause of this error message was the SQL Server Browser Service on the server hosting the target SQL Server Instance was not turned on.
An alternative is to connect using the port number. Each SQL Server instance is assigned a port number . The port number can be static or dynamic. The decision of static or dynamic is dependant on the DBA .
The workaround to the error 26 , where SQL Server Browser service is turned off, is to connect using a port number. When using the port number method, it isn’t necessary to specify an instance name.
A comma is required between the server name and the port number.
How to use a port number to complete SQL Server connection