Connection to SQL server fails for external VPN clients

Hello,

A long time ago I've setup my ISA2006 as a VPN server and since then my clients could connect to the internal network from home.
After rebooting one of my MS SQL Servers my VPN clients can no longer access this server via Microsoft SQL Server Management Studio ; local clients still work though. 

The strange part is that there are some other SQL Servers that work just fine. I've noticed that the SQL Servers that are facing the access problem runs multiple SQL instances that listen on ports different from the default 1433 port.

However this shouldn't be a problem since there is a VPN client inboud access rule that permits all traffic.

Logging shows that a connection is initiated to the SQL server on port 1434 (=this is the port that SQL Server listens to by default and tells the client on which port the instance is listening) by using the Microsoft SQL (UDP) protocol and the VPN client access rule. Next it closes the connection with result code 0x80074e20 FWX_E_GRACEFULL_SHUTDOWN.

How can I troubelshoot this problem ?

Thanks for your help.

Regards,


Joeri Michiels

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JM