Website can't connect to SQL Server, but console app can

Question

I have a SQL Server with two databases, a production database and a development database. The .net 2.0 website hitting the production database with manual SqlConnection code is working fine. The other database is being hit from a newer ASP.NET MVC app using Entity Framework 6.2 and is getting timeout issues. The timeout takes 30 seconds the first time, but the page comes back almost instantaneously on subsequent refreshes. Both websites are on the same box as the database, so are only using "localhost" to connect. They are using SQL Server user logins, not Windows authentication.

I copied the .edmx and .tt files into a .net console app and that app has no problem hitting the database with the exact same linq query and pulling the same data that is failing.

I then created a new web site and copied just that same code into an aspx page. It fails the first time with a timeout, and then works on subsequent attempts (and a week ago, the main dev site was doing the same thing).

I separated the dev database from the SQL Server 2008 R2 server and attached it to a newly installed instance of SQL Server Express on a different port, and get the same results.

The web server is windows server 2008 standard 32-bit. I copied both websites and the console application to a new box (I thought was 2016, but it turns out it is 2008 standard 64-bit) and get the same results.

The dev site was working up until a couple of months ago. The client was using local user accounts for everything, but had a domain and wanted to do testing with windows authentication for an old vb app that hits the same database, and I had started migrating testing accounts to the domain. When the client tried to later, for an unrelated reason, change his password, we discovered that he was already using a domain account, but that his laptop could not connect to the domain. We found several other computers that could not connect, even though the machines I had connected to the domain during my testing were working fine. An outside network "friend" was brought in to figure out what was going on. At that point, I lost all track of what was actually done. I know that different network and domain configurations were tried and didn't fix the domain issues, but I don't know what. However, the production site was never rendered inoperative.

I have no idea what is going on. Does anyone else?

Oh, and in case it was a provider issue, I've also tried manual connection using OleDbconnection from the web app, and it also fails with the Timeout issue.

Update: I spun up a new DataCenter 2016 box, installed IIS and .net on it and copied the website to that box. It has no problems hitting the database and pulling the data from the other server. I know patches and such were updated on the original box while the domain and network were being manipulated, but I don't know how far behind they were. I suspect that some patch changed some default or inherited .net configuration options or something. I did do a "repair" on the .net installation, and that didn't make a difference. However, with the production site working fine, I'm not currently willing to uninstall .net or anything else. I'm afraid I would risk pushing this same error into the production site and the client would be screwed.

Answer 1

It seems that for some reason, the timeout period elapsed while attempting to consume the pre-login handshake acknowledgement. Try increasing the connect timeout property in your connection string to 60 or more. Default is 15 (in seconds).

Example: Data Source=(LocalDB)\\v11.0;Integrated Security=True; Connect Timeout=30