ODBC connect failure to named SqlServer Instance

  • Hi,

    I had a strange proble connecting to named Sql Server instance.

    1. Some workstations worked OK

    2. One server did not work - 'Server not found...' servername\prodinstance

    3. All traffic were routed (NAT) through a firewall via same IP which was allowed in the firewall

    4. When I had tried everything else I finally asked them to start one other SqlServer instance on the same machine and tried one database there ==> worked OK AND

    5. My problematic named instance was suddenly found as well!!

    ??? why

    Ville

  • Hi Ville,

    my first hint would be to check the MDAC version on the client machines. MDAC 2.7 or newer is required to access named instances.

    Regards,

    Goce smilevski.

  • Hi Goce,

    the thing is that the connection to the desired server works when the other SqlServer instance (on the same server) is started and dies shortly after its shutdown....?

    Ville

  • I would hard set the port of the named instance if it is comming throught the firewall. The listener will pick a random port if 1433 is already taken by another instance on the same server.

     

    Wes

  • Hi Wes and Goce,

    thank you both for your efforts

    The instance is now allowed via tcp/ip,port and it works okay. It can be rather difficult in these kind of situations: The server resides in company A server hotel, it is run by company B, data connections are taken care by company C and the customer is company D, which I am working for as an external

    Ville

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