no VPN, good public connectivity - yes VPN, no public connectivity
When I am working from home, and tunnel into my company's system via VPN, I can work on my company's network but cannot get to external sites such as Google or Yahoo, or Microsft Live Meeting.
When I am in the office, connected to my company's WLAN, I have no problem working both on my company's network AND external sites such as Google, Yahoo, or Miccrosoft Live Meeting.
Doesn't sound to me like it's my home service provider because I can get to any site as long as I'm not tunneled into my company's system.
It sounds like you are using a 3rd party wireless network manager, like HP's and when setting up your VPN you or a company tech created and saved a profile for your home. In that profile you have limited connectivity, only the VPN. At your office you have another profile you connect with that is not limited. All you need to do is modify your home profile to allow actual internet connectivity or create another one that is unrestricted.