This is a bit outside my area of expertise, any pointers welcome. The MD of a company I support has moved to Spain, but wants to access certain UK-only services. I have set up a Squid proxy server on a box running XP Pro. It has an ADSL connection via an ethernet router. If I set my browser on my (remote) pc to use this proxy, specifying an internal address (192.168.x.x) and port 3128, once I have established a vpn connection, it works just fine. When the MD brings his laptop to London and is connected via the main corporate network, he is also able to connect via the vpn to the proxy server and it works just fine. Using his ISP in Spain or Vodafone 3G access, however, nothing happens. I am assuming the ISP blocks the port. Is this likely to be the case and if so, how can I find a port that isn't blocked.
Many thanks for your help...Chris