I have two SQL versions (SQL 2012 and SQL 2016) installed and running concurrently on a single server. After installing SQL 2016, had issue connecting to the newly created instant. 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: SQL
Network Interfaces, error: 28 - Server doesn't support strong text
requested protocol) (Microsoft SQL Server, Error: -1)
Can't find much on the Net for the precise solution to this specific issue. Eventually after almost half a day googling, the problem was the network protocol (TCP/IP) was disabled by default. After enabling TCP/IP, the connection works like charm!