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 clients can no longer access this server via Microsoft SQL Server Management Studio.
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.
Sorry for the late reply but I had to finish another project first. Unfortunately running a network trace (wireshark) on the internal interface of the isa server doesn't help me find the solution. A screenshot of what I see is on https://vandijk.sharefile.com/d/s46a514324414cd69.
The vpn client (ip 172.27.1.7) is first establishing a connection with the cluster (ip 172.27.4.46) via port 56230. Next it establishes a connection with the individual server (ip 172.27.4.38) via the same port. Then I see the same thing happening again but this time on port 56231, 56232, 56233, 56234, and so on.
It looks like the first connection attempt on port 56230 didn't work and its trying on those other ports now, apparently in increasing order.
However the network trace doesn't some any errors or messages that could help me troubleshoot this problem.
Microsoft SQL Management Studio times out after a few moments with the following message : Cannot connect to sqlserver\sqlinstance A network related or instance specific error occured while establishing a connection to SQL Server.
I'm still not sure what the cause of this problem can be.