https://forums.cox.com/discussions/internet/upload-speeds-drop-at-the-same-exact-time-every-night-for-months/127309
This is eerily similar to my issue. I'm pretty sure this is just an issue where cox isn't allocating enough resources to my local node. Either way, this has been a consistent issue for going on months now.
The post you referenced was 5 years ago, before DOCSIS 3.1 really took off. There is more upload bandwidth these days so issues like that aren't as common. Your area would have to be very populated and oversold for that to be a issue to the extent you are having. Also, seem to be having a upload AND a download problem. If it is congestion on the node, there isn't much you can do except file a FCC complaint and hope Cox does a node split, but that is unlikely since it's expensive. Hoping signal data gives more clues on the root cause.
