Fluctuating Upload Speeds

Just experienced a similar issue (non-existent upload speeds and 15-50% packet loss) over the past several weeks so I feel your pain. Cox-authorized contractors ran/buried a new line to my house, replaced all barrels between the tap and my connection inside (very few since I have no splitters between the main line and my house)- all to no avail. Luckily, I work from home so I was able to call them back each and every day I had the issue to schedule another technician the following day. After all, the squeaky wheel gets the grease... In total, it took 7-8 phone calls, 5 technician appointments, 5-6 live chats, and two bucket truck visits to the neighborhood to prove to them it wasn't an issue with my modem, my router, or the new modem I purchased temporarily to prove it wasn't my modem.

As I had suspected all along due to my signal levels, it was noise upstream from me at our local node that was affecting everyone in the area. Most customers who don't need the upload speeds wouldn't necessarily notice the issue, but I could definitely tell when it started around 7pm and lasted until 2-3am. Cox tried to charge me over $150 for the tech visits and new line run to the house, but I spoke with the Loyalty team for over an hour to complain and had them waive it all since the issue was on their end all along.

Luckily, I finally had some great experiences chatting with one of the good contractors who had the cell numbers of a local Cox data technician (important to request that since some specialize more in cable TV), and one of the bucket truck drivers who took the time to listen to my issues and work out where the problem was. When the last bucket truck guy stopped by the house, he solved it within 2-3 hours of being in the neighborhood. Sadly, not every contractor knows enough to help you and will mark your ticket as being an issue on your end if they don't know how to solve it. BUT, when you get a good one who truly cares about their work, you can tell. When the final ESR ticket was marked as resolved a day or two later, the contractor even texted me a screenshot of what he could see on his end and wanted to make sure I was getting the speeds I pay for. THAT'S customer service.