We are having issues with our SQL Server. About two times a day we have to restart our server because SQL becomes unresponsive to our web applications.
It doesn’t look like we have a problem with to many connections, as there are never more then 20 active at a time.
The weird thing is I can access SQL from MS SQL Enterprise Manager 8.0 only. Connections from any other application (ASP.NET or SQL Server Management Studio 05) time-out.
Queries work fine in Enterprise Manager, so I don’t think it’s an issue with locks either.
If the SQL Server log is clean AND (you can connect to DB locally OR remotely) AND a reboot restores your app to a known state then it suggests a pooling problem and/or network problem
We had a similar problem that was fixed for no stated reason by upgrading to latest service pack. Our problem manifested itself in the box keeping the underlying network connections open while the web app thought they were closed, so it would try to reinstate the pool and then run into max connections. Your question states you have not hit max connections but your symptoms are similar. Take a look at the network connections from the OS level.
Can you connect from the same box that hosts your web apps, but using another client app, like Query Analyzer or even bcp or isql from the command line?
Another thing to wonder: if you are able to connect from a web app box, can you USE the db your app uses? If so can you do things once you are in there?
What are the parameter settings for connection pool of web app? Have you tried adjusting these?