I have researched a lot on this issue but can't seem to find a solution for it. I have a named instance created on a server but I can't connect using the Servername\InstanceName. I am using SQL Server 2016 Enterprise Edition. Here is the setup: Servername: QA1 Has default instanced installed and also named instance: BUInt0 The SQL Browser service is started and I checked and UDP 1434 is allowed. When I tried to connect from a remote server, I cannot reach it using QA1\BUInt0. I get the following 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) (.Net SqlClient Data Provider) But it works if it use IPAddress\BUInt0. I had my system engineers check DNS but they don't see any issues. Anyone have any ideas what is going on and why I can't connect using Servername\NamedInstance format?

I have noticed there are two SQL Servers installed on the same box, which are 2014 and 2019; however, when I log into SSMS and type select @@version, it is showing 2014, and the instance name is showing as servername\sqlexpress. I am wondering how I can find the instance name of SQL 2019.

I have a named instance installed and have it set to use TCP port 1433 instead of Dynamic ports. The SQL browser is running and TCP IP is enabled. I have to put the port number 1433 on ssms and without including the port number it wont connect. Please advice what am I missing here. Is this a firewall issue or am I missing something.