When I try to access a named instance of Microsoft SQL server 2008 R2 SP2 on the local network, I have no problem. But when access it outside office from the internet, I can not connect to the database server.
It send back the "famous" following error:
A network-related or instance-specific error occured while establishing a connection to SQL Server. The server was not found or was not accessible. Verify the instance name is correct and that SQL Server is configured to allow remote connections. (provider: SQL Network Interfaces, error: 26 - Error Locating Server/Instance Specified)
This error happen in the winforms application and through the SQL Server Management studio.
The server instance name is correct since I can use it on the same local network. I precised that the server is a domain name such as "sql2008.domainname.com\sqldbname". I also make sure to configure SQL Server to allow remote connections from the SSMS > Server Properties > Connections > Remote connections.
More precisions: SQL Browser is up and running. TCP/IP enabled. No problem when installing the database server.
I did a lot of research the last few days and tried everything... I do not have any more ideas.
The system administrator responsible for this server assure me that the ports 1433 and 1434 are open on the database server. I can ping the server from home and when i use putty the command telnet host port I got no error. The command is waiting for me to type something.
Do you have any other ideas that may cause this problem? Port forwarding, etc?
Thank you, LB