First, welcome to the site.
I don't currently have Cox but I used to work for them. What times during the day/night does this happen. The most likely cause for this is that you may have a bad route to some servers during the day. There are many factors that come into play when it comes to the speeds you should be getting. For instance, I have a 40 Mbps connection with Qwest. I get 40 Mbps all of the time. But during curtain hours of the day I get way worse speeds to the server. Now, I own this site... and I'm always paranoid about the performance of the server to the client. Because let's face it, if the server can't keep up with sending and receiving results will be inaccurate. So I look into the test database and it clearly shows that other people testing at the same time were able to log 20 - 30 - 40 Mbps scores... so it's not the server. Then after a traceroute investigation the culprit rears it's head.
to run a traceroute...
First, go to your command promt.
- Go to the start menu, go to RUN, type CMD (this pulls up the command prompt)
Second, type
- On PC -- tracert testmy.net
- On Mac or Linux -- traceroute testmy.net
cut and paste or upload a screenshot here and we'll take a look at it. Run a traceroute to google.com as well. And we need traceroutes during times when you're seeing the problem and when you're not. It's good to get something to judge it against. Basically to get from point A to point B on the internet your information has to go through a bunch of Hops or other routing computers. If there is too much traffic in one area at once then you'll get stuck waiting in line (basically).
I may or may not be able to answer this myself, I'm developing right now. But we have tons of friendly people here who may catch this before I have a chance.
-D