My program connects to a MSSql database. If it connects via LAN it works fine, if it connects from outside I get the error message 0x80131904 Error when logging in the user 'ProgProj'. (translation might not be the same as on the english version. On the german version its like that)
I can exclude a port problem, because when the port was closed the message was that the server was not reachable. After opening the port it says it cannot login. But the login works on LAN with the very same Username and password.
What could be the cause of this problem? thanks!