VPN not assigning IP address

Not sure if this is the right place to ask this but I have a Nighthawk X10 with the regular Netgear firmware.  I have enabled VPN and connec t to it with a Mac using Tunnelblick.  It connects fine and I can access local resources on my home network.  But my computer's public IP address does not change.  Tunnelblick says this is a Netgear problem.  So far Netgear support has been no help.  I'm not sure where else to turn to for help.