1. Are you hard wired or wireless? I've found that people generally have a better more stable VPN connection when they are hard wired then when they are on wireless.

2. Are you at a hotel? I've found that VPN connections from hotels can be hit and miss. As an example if it's a hotel that has a lot of people staying at it for a conference of some sort, chances are that the hotel internet connection can only handle so many simultaneous VPN connections. I typically tell my end users to just keep trying and hoping they get an open slot.