High number of concurrent logins from same PC to SQL Server

I am performing a load test on a Sql Server (2008 sp3 Standard) environment. In order to simulate a high number of concurrent logins, there are 8 terminal servers each running 100 separate windows sessions. Each session is running a single instance of an application which logs onto it's own database on the SQL Server using a unique username for that session. The problem I am running into is after the ~250th login, the application cannot reach the SQL server anymore. Using management studio also yields same result. TCP and UDP ports are open. Telnet to port 1433 timeout. SQL logs don't even show it successfully or failing to log in.
I've made sure the Sql server is configure to unlimited concurrent connections. There's plenty of memory, CPU, network.
The only thing I can think of is SQL Server sees the 8 terminal servers and is blocking too many connections from a single PC although connecting with different users to different databases. Any insight would be appreciated.
Who is Participating?

[Product update] Infrastructure Analysis Tool is now available with Business Accounts.Learn More

I wear a lot of hats...

"The solutions and answers provided on Experts Exchange have been extremely helpful to me over the last few years. I wear a lot of hats - Developer, Database Administrator, Help Desk, etc., so I know a lot of things but not a lot about one thing. Experts Exchange gives me answers from people who do know a lot about one thing, in a easy to use platform." -Todd S.

Dave BaldwinFixer of ProblemsCommented:
Maybe you're using up the available resources on the client side?
Vitor MontalvãoMSSQL Senior EngineerCommented:
Looks like you've found the limit of your SQL Server instance.
What are the specifications of the server? What are the Window Server and SQL Server versions?
jkimautocribAuthor Commented:
We resolved the problem. Turns out that the virtual Win2012 R2 server which was acting as the router has a limit as to how many TCP socket connections it can support. Switching to a Fortigate firewall resolved the problem. I've googled and found no directly related discussions on this limitation on Win2012 as a router.

Experts Exchange Solution brought to you by

Your issues matter to us.

Facing a tech roadblock? Get the help and guidance you need from experienced professionals who care. Ask your question anytime, anywhere, with no hassle.

Start your 7-day free trial
jkimautocribAuthor Commented:
Other comments were not directly pertinent.
It's more than this solution.Get answers and train to solve all your tech problems - anytime, anywhere.Try it for free Edge Out The Competitionfor your dream job with proven skills and certifications.Get started today Stand Outas the employee with proven skills.Start learning today for free Move Your Career Forwardwith certification training in the latest technologies.Start your trial today
Microsoft SQL Server 2008

From novice to tech pro — start learning today.