3Com office Connect ADSL firewall router and VPN

[MDgeriatric]

I have recently purchased a 3com ADSL wireless 11g router. I can access the internet using my company laptop using the wireless USB adaptor, and also connect if using the wired lan port. The problem is I cannot connect to our Corporate Lan (we use checkpoint secure remote). Other people I work with are using both Draytek or Netgear wireless routers without any problem (or any additional config).
NAT is turned on, and IP-SEc passthrough allowed.
3Com have advised me to add additional ports to the virtual server. I have added the ports I believe are necessary, but still cannot connect. Has anyone else tried this router in this config?