Today is a good day to code

ASUS ac66-u Losing Internet (WAN) Intermittently

Posted: May 1st, 2015 | Author: | Filed under: Uncategorized | No Comments »

Over the past few months, I’ve been having a strange problem with my Asus ac-66u weirdo router and I’ve finally found what I think is the fix.

Every week or so, the router would stop allowing access to the Internet, while internal networking seemed to work well.

I would try everything to fix it, but only a restore to factory settings and a reconfiguration would allow me to get back online.

Loading saved settings would always being the problem back. This problem has persisted through every firmware update I have applied since I bought the router over a year ago.

The other thing that I would notice was that when the problem would occur the bandwidth monitor would show well over a terabyte of data being received.

I took this to be a glitch of some kind since it shouldn’t be possible to receive that much network traffic from the WAN connection. I was mistaken.

Under the ipv6 section of the settings there are two drop down menus. One makes your router a ipv6 responder for your internal network ( or the Internet if you really want ), the other advertises is services as an ipv6 host.

For inexplicable reasons the default is for the first drop down to be disabled, which is good, but the second drop down is defaulted to enabled! So your router advertises ipv6 services to the Internet even though the former has been disabled!

This results in terabytes of UDP discovery packets being fired casually your way making it impossible to receive real data.

Setting both drop down menu settings to ‘disabled’ fixed the problem. Everything, including the bandwidth graph is normal.

I can not fathom why advertise is set to enabled by default, it makes no sense. Hopefully ASUS will change it to disabled by default in a subsequent firmware update..