I use Cisco AnyConnect VPN.

When tethered to my iPhone, my Windows laptop connects to VPN just fine. My Mac laptop appears to connect, but I'm actually cut off from all internet access. Even ping fails -- "no route to host."

I asked our IT helpdesk and they said this was a known issue with iPhones and Macs -- something about DHCP, I don't quite remember -- and they recommended I connect to VPN through a Windows virtual machine.

That solution is too convoluted for me. Does anybody have other ideas?