butrflysmooches....your posted modem results above look very good power and SNR, however, those Correctable's has to be bad. Maybe someone like WiderM can speculate on why such items appear.
You run the Cox or other speed tests and see down/up speeds and you say it goes bad about 12pm. Are you Streaming video's to watch, like youtube, etc. Should this activity only affect the download side. Or, are you playing interactive games that need the upload? Have you also done these activities when the speeds were better. I was just curious if you do the same down/up activities during the good and bad times. I'm sure you can "feel" when you speeds diminish.
I've also watched my TaskManager/Performance/ and select Ethernet or maybe Network to see the send/receive Mbps while doing your activities. Hang in there till you are satisfied. I wish COX would fix my inability to insert Images into this reply box. I'm jealous when I see inserts that you and many others can do.. Mine just doesn't work.