I'm not familiar with your 3G wibe router

Have you looked into the USB interface of the 2820 , as you can join up a 3G wan that way ,

Hi yes I am aware, but the USB 3G connection on the router isn't an option for me, hence the 3G router connected via Ethernet...

I have reviewed the WiBE online now...

I'd try by disabling dhcp on the WiBE , give it a static IP ie 192.168.0.1 and tell it to use 192.168.0.2 as a DMZ ( De-militarized Zone ) so you don't end up with 2 Firewalls, ensure the 3G WiBE is connected and check its DNS settings its picked up via 3G and gateway and its WAN connection ,write them down.

Connect 3G WiBE to WAN2 of 2820 , give WAN2 on 2820 static ip of 192.168.0.2 with the DNS of what you written down and gateway of first try 192.168.0.1 if doesn't work change gateway to the 3G WAN interface

Hope that helps

which do you have HS7 or HS21 ??

Hi, I have the HS21. Apparently its a new model and there is no manual out for it yet?

that one was released in October 2012