Did you say DSL? Do they use PPPoE?

I'll bet you 10 antipoints your problem is with the Path MTU.

My coworker had the same issue a couple weeks back: dsl line, cisco vpn, cheap router.

Cisco's vpn client runs it's own ip stack, and tries to do path mtu discovery. The mtu is configurable in the vpn client. Set it to something like 1492.

I guess diagnosed/debugged this when my coworker explaied his situation to me; I asked him to do some packet captures to be able put the finger on the precise culprit, but he hasn't had time to run those yet. Still, setting the MTU of the vpn client worked.

Give it a try.

Ammo