HORRIBLE internet speeds last few weeks

Cable come into the wall, into a cox supplied splitter - one side into Cable Modem / Telephone box combo (Cisco DPQ 3212) the other into my HD DVR, BUT to save the Cox techs some time I have also tried without the splitter and my signal levels improved from -14ish to -12ish but speed didn't change, after the switch I rebooted the box just to make sure, it's back the ways its been for the last month and a half when I was getting 65Mbps with the exact same setup.

Tiffany,

Thanks for the reply, I have a tech scheduled to come out Wednesday evening between 5 & 7 pm. I will update after they come. 

Deville,

When are your speed levels slow? Mine are usually crawling slow around 8-10 pm in the Phoenix area. I got 105 mbps this morning and 3 mbps right now. Tested in COX's speedtest and it's awfully slow at 3 mbps. NOT 30, 3!!!!!!! I hope the speed gets better...

Mine are slow on weekends and late nights when people are home and on their PCs. COX keeps telling me that the number of users does not interfere with my speed, but NOT true. The more people share the network, the slower it gets. 

The power levels on the downstream should be no less no more than -15/+15 dBmV and some of those are getting pretty high especially channel 8, I suspect channel 4 did the same and went over the -15dBmV threshold and gave up trying (or exhausted attempts) to bond the channel.

The upstream channels don't look that bad actually, typically start seeing issues when it caps at around 55-58 dBmV, so uploading doesn't look bad at all.

In my experience as a T2 tech support this looks like a modem/wire swap is in order as you have 1-2 (channels 4 + 8) confirmed dead-ish downstream channels and what appears to be 2-3 (channels 5-7) about to go. The closer to a single digit power level the more consistant the result whether pos(+) or neg(-). Sporadic jitter related to the well documented speedtests you listed are indicative of the downstream issue.

Swap it for a decent Motorola 6121/6141; and have a tech check wiring outside. Keep far away from the combination wireless gateways; they are infantile thus-far in their deployment and the firmware is not very well written.

So first let me say thanks to whatever tech came out first for the "official" diagnosis and the second for redoing my wiring.  My speeds are fantastically improved now and it looks like the speed doubling as taken affect in NW Florida (Fort Walton Beach / Pensacola Areas)? I'm on the premier package and setting well into the high 80's on download now whereas last week after the fix was mid 60s.  I may still need an amplifier but for now it works!!

At what time did you measure the speed? Do it when it's saturated after 6 pm.