Okay, lots of posts here, and some of it seems contradictory. Here's what I've done and where I'm stuck.
I have a set up where BOTH a coax and an ethernet connection come to the Actiontec MI-424-WR router. I don't know why, that is just how Verizon set it up.
I removed the ethernet cable from the WAN port of the Actiontec and plugged it into the WAN port on a Time Capsule, the configured the TC for PPOE (which is what Verizon uses in Northern VA). No dice.
I then called Verizon about the username/password required for PPOE and they told me it can be ANYTHING. Sure enough, I entered user/password and the TC connects me to the internet just fine. I also have an Airport Express, so have a full N wireless network in the house.
The TV, including the programming guide still works, but here is the hitch. The programming guide will regularly stop working after 2 days. This is surely due to the DHCP lease from the Actontec expiring and the settop box can't pull a new lease from the Actiontec, because the Actiontec is no longer connected to the WAN ethernet wire (the TC has that).
I tried connecting a LAN port from the TC to the WAN port on the Actiontec. Doesn't work.
If I can fix the DHCP lease expiration, then it will work flawlessly. As it is now, it works, but every 2 days, I have to briefly reconnect the Actiontec directly to the ONT via the ethernet wire. Annoying.
If this isn't clear, I'll try to supply more information.
Why go to all this trouble? (1) full N wireless in the house, (2) better compatibility with the 2 access points (TC and AE from the same vendor).