I do a speedtest.net test every morning. Things have been on the fritz the last 3 weeks or so for my 6 mb DSL service over AT&T lines. Usually get 10ms ping and 6.5 download from the Comcast server and Colo servers. My IP has also been changing about 3 times per day the last 3 days.
Ping is 45 ms this morning, the worst in 3 weeks and 1.5 mb down. I also have backup 768kb DSL Lite on the other phone line with AT&T. Same poor ping numbers and choppy speeds.
I hate calling support and going through the hoops. BTW, I also swapped the Zyxel 642M and did the test with a stand alone laptop bypassing the router. Same results.
I talked to support this morning and they ran a line test. They asked that I connect the Zyxel 642M to the outside box. It's a pretty day and I had the time and a spare 642M. Speed was a little better, comming in at 3 MB. Then it jumped to 5.5 MB. Tech said it looks to be an internal network issue. I agreed. Not much later, I was down to 1.5 MB again. This spare 642M I had marked slow Netflix a couple of years ago.
Long story short. Another 642M arrived a few days ago that I won on eBay. What the heck. I'll upload my settings and give it a try.
OMG, it looks like 6.5 MB is back. I think I have 2 failing 642M's. To many thunder storms a few weeks ago.
I know this is a late reply but congratulations on finding the solution to your DSL slowdown.
Also I wanted to share that those P642's are getting pretty long in the tooth so you might want to consider trying out one of the P660R-ELNK Router/Modems that have a more recent chip set and firmware (ZyNOS Firmware Version: V3.40(AGE.4) | 12/07/2009 which I updated to using Earthlink's updated firmware utility) that can be had on the eBay auction site also and are just as economical in price as the much older P642's. -- Whats the point of owning a supercar if you cant scare yourself stupid from time to time?