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.
jkimautocribAsked:
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Dave BaldwinFixer of ProblemsCommented:
Maybe you're using up the available resources on the client side?
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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?
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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.
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jkimautocribAuthor Commented:
Other comments were not directly pertinent.
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Microsoft SQL Server 2008

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