I have an ER5120 router and an AT&T 3G Microcell, and I cannot seem to figure out the best way to get the Microcell connected to the network. I have been able to get the Microcell working on a regular Netgear home router, so I know it works behind a router. That particular router didn't require any configuration, it just worked. The issue is that when it's connected to the ER5120, the Microcell shows the constant blinking of the cell network icon (bottom one), and won't register a handset. Here is what I have done so far to try and get it working: (1) Microcell has a DHCP reserved address (2) Router has Virtual Server ports open for that IP address: 123, 443, 4500, 500 (3) Router has Firewall IP-Mac binding set for Microcell MAC / IP (4) ARP Spoof is on / off. Didnt make a difference. (5) Router has Firewall -> Access Control -> Services enabled with same ports / services as listed in Virtual Server. ----- I'll admit, the router is new and I don't know everything about it yet. But I assumed that's all it needed to have the Microcell work behind the router. Hopefully I'm missing something simple. Thanks for anyone that might be able to provide some guidance.