Router-behind-router setup for a Uverse 2Wire 3801HGV

Posted on 27 March 2014 by jose

I'd recently been having problems staying connected to my Uverse wireless router (a 2Wire 3801HGV residential gateway). Frustrated by this and the fact that the highest speed it could support was 802.11g (a max of 54 Mbps), and given the large amount of wireless devices on my network, I decided to spring for an ASUS RT-N66U dual-band router. I don't have too many devices that can go on the 5 GHz band yet, but it's nice to have for the future, and in the meantime, with my plan to add a NAS to the network, having internal transfer speeds capped at 54 Mbps just won't do.

There's a number of methods to get a router-behind-router network to work. My preference was to let the ASUS router handle all the IP assignments, firewall settings, and the like for the wireless and wired network. The 2Wire would essentially lose its wireless functionality, which was giving me so many issues anyway, though it would still assign dynamic IPs on its wired ports.

Disabling the wireless on the 2Wire RG was simple. Adding the ASUS on one of the 2Wire's Ethernet ports was similarly easy. Best of all, with my wireless network set up already on the ASUS, I found I immediately had wireless Internet on my laptops. Everything looked good... until I tried to get my Xbox to work. I keep in touch with a number of friends from all over the world via Xbox Live and multiplayer gaming, so to have this not work was disappointing. I knew getting the Xbox and Xbox Live to work would be tricky, and I was right.

Disabling the wireless on the 2Wire was only the first step, I discovered. I also had to open ports on the ASUS router for Xbox Live as well as game-specific ports on the Xbox routes. Even after that, my connection to Xbox Live was still pretty flaky. I went back to the 2Wire's configuration interface and attempted to put the ASUS router on the 2Wire's DMZPlus mode, which would in theory route all traffic to the ASUS to let it handle as it saw fit. Parenthetically, I was surprised when everything seemed fine with the ASUS behind the 2Wire and the 2Wire not having the ASUS listed in its DMZPlus mode, but my approach to networking these two devices was always to leave as many settings alone as I could get away with; thus I did not touch the DMZPlus mode or the Advanced Firewall settings until I absolutely had to.

Even with the ASUS in the 2Wire's DMZPlus mode, I could not stay connected on Xbox Live. Things would appear to be fine up to a point, and then the Xbox would freeze or the Xbox Live party would crash, or both. Something in the 2Wire was not agreeing with the ASUS. I disabled all of the Advanced Firewall settings related to packet blocking, again with the intention that the ASUS would handle this and the 2Wire would simply be a modem passing a connection to a router. Even this did not solve the problem, so I delved deeper. Looking around in the 2Wire's settings, I eventually found the Cascaded Router mode, and once I added the ASUS as a Cascaded Router, I was finally able to get Xbox Live and online gaming to work.

I haven't tested whether the Cascaded Router setting obviates the need for the DMZPlus mode, or whether it sets it automatically (much like the 2Wire's "router-behind-router detection" setting, which does what it says on the tin, finding a router plugged into the 2Wire and asks whether you want to treat it as such, with the end result being that the ASUS router would be placed in DMZPlus mode), though with my network currently appearing to be stable, I'm disinclined to modify my settings to deliberately introduce instability at this point. I've similarly left the 2Wire's Advanced Firewall settings disabled, trusting to my ASUS NAT/Firewall and the security of my Linux machines (dual-boot, though I maybe use the Windows partition once a year, if that).

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