I just bought two 3G broadband wireless routers. One is a netgear mbr624 and one a zoom 4051. The features are similar except the zoom has a failover feature from wired broadband to 3G that sounds cool. I'm comparing the two.
I have a verizon U760 3G usb device that works great plugged in to my pc, or either of the two routers - except - the zoom router seems to be blocking vpn passthrough. I use pptp with both endpoints on windows pcs, nothing fancy.
The pptp tunnel gets to the authenticating part then hangs at "verifying username and password" and that's all she wrote.
I don't know much about how this stuff works, but the vpn passthrough is pretty important for what I do. The zoom has latest firmware and works ok except for the passthough. The remote end of the pptp logs a cryptic error, so it's getting that far.