I have the same problem. Before I had Verizon FIOS installed, my PPTP to the home office worked fine. Now, I can only connect every now and then, through the Verizon Router (Actiontec MI424WR). I have been told that the router memory for this service is not large enough for the TV/Phone services and to hold the IP Addresses also. Therefore, I was told I had to "reset' and/or turn the router off and back on to clear the memory. This has not worked. Any other suggestions? If I can't get connected to my office, then I guess I have 2 options, 1- lose my job or 2- lose Verizon. I know which I am going to choose!!
I currently have Windows XP. May be going to Vista Home soon though. I don't think the Operating Systems matter in this case though. It is the Verizon Router that is blocking the outgoing connection.
If you are the original poster (OP) and your issue is solved, please remember to click the "Solution?" button so that others can more easily find it. If anyone has been helpful to you, please show your appreciation by clicking the "Kudos" button.
VPN's is always a hard to understand subject. FiOS will in fact work with any VPN service. A lot of the time, the internal VPN network [192.168.1.x] is the same as as your home network which causes the router to freakout because now it sees to of the same network and doesn't know how to route traffic (nat table issues). Solution: Change the network of the office or the home to a different network. For example, 192.168.10.X or anything other than default. There are also settings in many VPN servers to fix this exact issue. Remember, if you have no issue with http traffic (aka web traffic) there is nothing stopping you from using VPN services.
Routing is seperate factor. Are you able to ping the VPN server?