VPN with Linksys WRT54G v5

I have a Linksys WRT54G v5 router and everything works OK except I can
not open a connection to my friends VPN. Does anyone have any tips?
Is this a known problem with v5 of the WRT54G? I already called
Linksys support and tried their suggestions, but they did not help. I
even tried disabling the Linksys firewall completely, but still could
not use VPN. I get an error 619 or 721.


Linksys suggested the following:


Cisco Interface (If your Setup page has a Cisco Logo)
- Click on the Applications and Gaming Tab > Port forwarding > Enter
the ports needed to be opened > Click Save Settings


Regular Linksys Router Interface (If your Setup page has a no Cisco
Logo)
- Click on the Advance Tab > Port Forwarding Tab> Enter the ports
needed to be opened > Click Apply


(E.g. Given ports: 47- 47 - UDP&TCP, 50 - TCP, 500-500 - UDP
and 1723 - UDP&TCP for VPN Application). For the IP address: Enter
the IP address of the computer behind the router that will use the
application: E.g. 192.168.1.101


Customized Port Ranges Protocols IP address Enable
Application From ~ To TCP UDP


VPN 47 ~ 47 / / 192.168.1.101 /
VPN 50 ~ 50 / 192.168.1.101 /
VPN 1723 ~ 1723 / / 192.168.1.101 /
VPN 500 ~ 500 / 192.168.1.101 /


Hope this helps.


Thank you and have a nice day.