Teck, if you right click on the image and select view image you can see the uncorrectables, still no upstream levels. Only ch 16 shows uncorrectables, 9766, all others are zero. Ch 16 shows 2015 corrected, all other channels 9 to 121 corrected, not bad for 2 days up time.
Looking at the uncorrectables, most of them seem to be on the downstream channels with the weakest signal. Looks like a issue with old coaxial wiring. Does OP have RG59 maybe? If not, how does the cable get from the street to the modem? Splitters? Amps?
Also, what did you mean by "much slower"? What speeds are you getting? Is it slow download, upload or both?
The speed just seems much slower, I generally browse the same sites. Reddit, etc... and I guess the new modem would be as fast or faster. So far it seems slower. I ran some speed tests and some say its around 150 others were 76 and 65...
Actually your corrected codewards (corrections) are not high, mine is 10 million after 4 days. Your only problem is the ultra-low power on channel 16, you might need cox to check your cables.
Note: a low power isn't always bad, averages about -8, but still able to watch 4k and game on multiple devices with no problem. Having low power and much higher than average correctables and uncorrectables on one channel is bad.