On a laptop running Windows 7, I can connect to the VPN server at the office on the Ethernet connection. The VPN server is running on Windows Small Business Server 2011, and I can do it on any other Windows 7 computer in the office.
However, one single computer doesn't let me run the VPN through the wireless connection for long. When it does connect, it disconnects between 5-15 seconds later, asking me to reconnect. I can connect to the VPN via WiFi on my Android phone, and on another laptop, so I know it's not the router.
I also tried disabling the firewall on the laptop in question, with no change. Tried a new WiFi card (internal), and a new WiFi USB adapter. None have fixed the problem.
What else would cause the wireless to not allow a VPN connection?