Navigate the the location below in your registry and make the corresponding change.

Create or edit the existing String value named "MaxConnections" and set it to the maximum number of connections, the default is 100. 

Restart Windows. 

Key:[HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\VxD\MSTCP]
Value Name: MaxConnections
Data Type: REG_SZ
Data:32-bit Number