What's the first part of your Subversion repository URL?
I can't guarantee the first four since it's possible to reconfigure everything to use different ports, of if you go through a proxy of some sort.
If you're using a VPN, you may have to configure your VPN client to reroute these to their correct ports. A lot of places don't configure their correctly VPNs to do this type of proxying. It's either because they have some sort of anal-retentive IT person who's being overly security conscious, or because they simply don't know any better. Even worse, they'll give you a client where this stuff can't be reconfigured.
The only way around that is to log into a local machine over the VPN, and then do everything from that system.