My Dell work laptop recently failed to connect to establish VPN connection to my office on TCP port 10000. via WLAN The problem was that it always says "failed", although I was 100% sure the VPN gateway was up and running (I tested with wired connection, it worked).
Googling around did not help much either, except one email on a discussion site. The guy said he had the similar problem and fixed it by disabling VPN priority or something like that. But when I checked the property of the broadcom WLAN, there was no such thing. The only option with word "priority" is "VLAN priority" which was set "auto". After disabling this, my VPN worked!
Oh, forgot to mention that I also reset the MTU to default. It could help too. I dunno.