“Client unable to establish connection because an error was encountered during handshakes before login. Common causes include client attempting to connect to an unsupported version of SQL Server, server too busy to accept new connections or a resource limitation (memory or maximum allowed connections) on the server. [SQLSTATE 42000] (Error 26) OLE DB provider "SQLNCLI11" for linked server returned message "Client unable to establish connection due to prelogin failure". [SQLSTATE 01000] (Error 7412) OLE DB provider "SQLNCLI11" for linked server returned message "Client unable to establish connection". [SQLSTATE 01000] (Error 7412).”
The occurrence of this error is triggered when the connection limit for the Linked Server (database) is reached.
The “Max Connections” setting in SQL Gateway refers to the maximum number of concurrent connections allowed to access the Linked Server at any given time. Each time a client application or a software program, including an SSMS instance, connects to the Linked Server, it occupies one connection slot. When the number of connections reaches the “Max Connection” limit, any additional connection attempts will be rejected or queued until a connection slot becomes available.
To resolve this error, the solution would be to increase the “Max Connections” setting on SQL Gateway. By doing so, the server will allow a higher number of concurrent connections, effectively mitigating the issue and ensuring smooth connectivity for client applications trying to access the Linked Server.
