My ISP has given me static IP's on the 3G modems eg 172.23.1.30, 172.23.1.140, 172.23.7.145, 172.23.5.56 when these 3G modems are connected to the network from the LAptops i can they can ping each other. When i connected these to RB411U's they are not able to ping each other. i am only able to make 2 routers ping each other by setting the other routers ip address as the remote address in the ppp client setup and vice versa. In short i am able to have 2 PTP links. What am looking at achieving is to use one of the 3G modems as an gateway to the other modem. which means all should be able to ping the 3G modem i presume to be the Gateway