I was trying to set up a friend’s Xbox 360 on my home network that uses a D-Link DI-624 router (Rev. C) with version 2.76 firmware and a brand new Motorola Netopia 2210-02 ADSL modem, but I wasn’t able to connect to Xbox Live.

My Xbox, which had been connected for months with an Open NAT while using a old Siemens Speedstream 4100 modem, never had any problems connecting.

I double checked all the connections, powercycled the Xbox, then ran the network tests from the System blade. It would pass all of the tests up until the Xbox Live test, at which point it would fail spectacularly and restart the tests – but this time displaying a “Disconnected” message at the Network Adapter test.

I bypassed the router and plugged the Xbox straight into the DSL modem and was able to connect, but with a Strict NAT. (I should have realized the significance of this right away, but I didn’t.)

So I reconnected the router and kept experimenting. After a while, I noticed that my computers connected to the router also lost their connections when I tried to sign in to Xbox Live.

As it turns out, the suspicious-looking disconnection message was accurate – something the Xbox was doing was causing the router to reboot.

I Googled around and found a few good posts about this problem.

First, I disabled UPnP on the D-Link router thanks to the advice in this Ars Technica forum post. Then I configured it to assign the Xbox a static IP address and then put that IP address in the DMZ. Now the Xbox was able to connect to Xbox Live, but the NAT status was Strict.

I wasn’t going to settle for that, though. I wanted to get an Open NAT.

So I took it out of the DMZ and port forwarded UDP 88 and both UDP & TCP 3074 ports to the static IP address, but the NAT status was still Strict.

Giving the Xbox a static IP address and forwarding the ports had fixed similar connection issues and permitted an Open NAT for almost everyone else, why wasn’t it working for this setup?

More Googling finally turned up the explanation. The Motorola Netopia 2210 contains a NAT router, so no matter what I did with the D-Link’s settings, I was going to keep getting the Strict NAT from the modem as long as it was handling the PPPoE. (This is what I should have realized earlier, when I was connecting the Xbox directly to the modem.)

The Motorola/Netopia 2210 is also a router with full DHCP functions and may not function correctly when connected directly to another router. Not changing the modem to Bridged Ethernet may result in double NAT’ing, increased latency, possible IP conflicts, or possibly a network that doesn’t work at all.
– http://www.dslreports.com/faq/15855

The solution was to configure the modem to use “Bridged Ethernet” mode and set up PPPoE on the router.

As long as you’re setting up PPPoE on the router, you may want to select “Keep Alive” or “Always On”, if those options are available, or set the Maximum Idle Time to “0”. You should also confirm that the MTU value is “1492” and that value is used on all the devices on the network.

Also note that the Motorola Netopia 2210 has an “Internet” light that lights up green whenever there is an active PPPoE session initiated by it. The light will stay off when the PPPoE session is initiated by a router or other device.