We have a Cisco VPN in our central office that's been working great for several years. We've never had a problem with any of our remote clients being able to establish a connection to the VPN. This includes home-based clients with slower connections like DSL.
Recently we moved our office (and switched to a different ISP). Since then, some (but not all) clients have been unable to connect to the VPN (the handshake never gets to the point of prompting for a userid/password).
Since certain clients are able to connect, I think we can assume that the VPN is working properly on the router side. The clients that are having problems are the home-based ones with slower, DSL connections which makes me suspect this is some sort of latency issue.
Any suggestions or advice on what we might do?