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A network-related or instance-specific error occurred while establishing a connection to SQL Server

  • August 26, 2011 at 11:23 am

    #1373989

    NJ-DBA (8/26/2011)

    I have to say- I find it surprising that one client it works without specifying the port number and another you must specify the port number. To me this means one client is allowed to access port 1434 while the other is not. Is this the case? the client which is able to connect without specifying the port number- is client actually running on the server, or this is another client PC just like the one with the problem?

    If I have all the information correct, and one PC can access without specifying a port, while the other must specify the port... and everything about these two clients is the same (i.e., no alias is specifed in the working client) then there must be an existing firewall rule which is allowing access to port 1434 by some host and not allowing it from others.

    what you want to ensure is that your SQL Server is allowing access to port 1434 from any host you wish to connect to sql server using the name... so you can either add the ip address of the new host to the list of allowed hosts, or you can do something like allow access to 1434 to ALL hosts, or all hosts on a certain subnet, etc.

    http://technet.microsoft.com/en-us/library/cc947832(WS.10).aspx

    this is for Server 2003/xp.... basically, you are looking to ALLOW access to UDP port 1434 from ANY or from the ip address of the clients you want to be able to access sql server...

    just to rule out an alias being involved, from the working client, launch "SQL SErver configuration manager", then expand "sql native client 10.0 configuration, and look under aliases... nothing there? if there is, that would mean that we are using an alias on the working machine, and that is how we are accessing the server by name... if so, you may want to ensure that the SQL Browser service is running on the SQL Server... if it is, and connectivity is allowed, then there is no need for an alias.

  • August 26, 2011 at 11:24 am

    #1373992

    Good catch NJ-DBA - sounds like that is indeed the case in regards to the rule allowing access from some and not others.

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