In short, with the help of the local ISP provider, we have been able to isolate the problem to that of the tomato software/router itself.
We had configurated the PPTP server within the tomato > VPN tunnelling menu option. So only used the GUI settings for setup. With the following settings:
Remote IP Address Range: same range as router, but not overlapping with the routers dhcp range. only 3 ip's were reserved.
Broadcast Relay Mode: both
All other setting as default.
The above settings will not give any succesfully connection from the internet, but will give a succesfull connection from the LAN.
Suggestions from users on different forums, advised to add an extra firewall script under Administrator > scripts > firewall:
iptables -A INPUT -p tcp 014dport 1723 -j ACCEPT
iptables -A INPUT -p gre -j ACCEPT
iptables -A INPUT -i ppp+ -j ACCEPT
iptables -A FORWARD -i ppp+ -j ACCEPT
iptables -A FORWARD -o ppp+ -j ACCEPT
iptables -t nat -I PREROUTING -p tcp 014dport 1723 -j ACCEPT
iptables -I INPUT -p tcp 014dport 1723 -j ACCEPT
iptables -I INPUT -i ppp+ -j ACCEPT
iptables -I FORWARD -i ppp+ -j ACCEPT
And to add the Port forwarding rule 1723:
TCP port 1723 external to internal port 1723 to internal address of tomato router.
All of the above still did not give any successful connection to the PPTP server from the internet.
The ISP techie also checked and made sure that all ip traffic is forwarded to the tomato router even made sure the GRE protocol and port 1723 is forwarded.
He also gave their modem the same public IP address, just to check and we also removed their modem and placed the tomato router directly onto the internet.
All was tested using a iphone through 3G and the ISP's own VPN client on his desktop. No response was received from the PPTP server by the VPN clients.
So, we both are at a loss now and have no idea what to do next.
I have read through and tried even to setup the PPTP server through the tutorial called (tut:configuring-a-pptp-vpn) however, I am not a programmer and am at loss if there are no complete steps given when entering commands into a shell application. e.g. I was not able to get past the editing of files and saving them.
We really hope there is someone out their who is willing to have a try and help us make the correct changes to the tomato router so that we can use VPN from outside the LAN as well. If you ask for making a shell connection, please give me the complete shell commands in steps so I can just copy and past them. This way I also learn them quicker. I do know how to get into the router using shell. :-)
Thanks a million for your assistance. Looking forward to your assistance.