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ipman
join:2010-08-31
San Jose, CA

ipman

Member

Finally solved my internet stability problem with DD-WRT!

Ever since I signed up with u-Verse service, I have been having constant connection drop out problem. I even wrote a ping script myself to check if I have any connection problem.

Initially it was that long download would freeze for no reason. Everything else seems to be fine except hiccups in YouTube which I blame cache. Then I started streaming video and it is bad. It is impossible to watch a movie using my Blu-ray player. And then, uploading pictures over flickr constantly fails.

And finally, I found the problem! It was my router, running DD-WRT. Compounded by the fact that U-verse is issuing a DHCP lease that is good for just 10 minutes! From what I understand, it means every 10 minutes, all connections on my router go dark.

The simple workaround is to run a firewall script:

iptables -I INPUT -p udp --dport 68 -j ACCEPT

to allow the DHCP packet to go through. Go figure!
bennor
Premium Member
join:2006-07-22
New Haven, CT

2 edits

bennor

Premium Member

The problem you experienced is a known issue when setting up your own router behind the ATT Uverse router. Ran into the same problem when I initially setup a TomatoUSB firmware router behind an ATT Uverse 2Wire 3600HGV gateway/router. There are several earlier threads both here and via a Google search the explain how to setup a 3rd party router (ie your own) behind an ATT Uverse router and to use the iptables setting you posted to deal with the connection drop issue every 10 minutes problem. The cause as explained in one of the links below is due to; "the DD-WRT SPI firewall is blocking responses from the DCHP server. UDP requests are sent to the DHCP server at 50% intervals, but the response is actually coming from a different server, and is thus blocked by the firewall."

Someone please sticky this
Help for u-verse noob

A Google search for DDWRT and ATT Uverse would yield these links:
AT&T U-verse with DD-WRT router in DMZ mode
AT&T U-verse 2wire Gateway and DD-WRT Router in DMZ Mode…
AT&T U-verse 2wire Router and WRT54GL with DD-WRT Problems

If your using a 2Wire 3600HGV, there is a huge thread over on the ATT forums site that discusses how to setup a router behind the 3600HGV.
U-verse for BUSINESS? : 2Wire 3600HGV bridge mode? or another AT&T supported VDSL modem?

Edit to add: The 10 minute drop issue is also mentioned in the forum AT&T U-Verse FAQ:
How do I configure bridge mode (DMZ+) on a 2Wire 3600HGV, 3800HGV, or 3801HGV?

"8. Restart your router, when it gets an address via DHCP again, it will be the public outside IP address. At this point, you can leave your router in DHCP mode (make sure the firewall on your router allows the DHCP renewal packets, which will occur every 10 minutes), or you can change your router's IP address assignment on the WAN interface to static, and use the same settings it received via DHCP."