Thoroughly confused...

It is highly unlikely there is an issue with your modem.

I have experienced, numerous times, issues with upstream speeds on Cox. I had to go as far as threatening to cancel a couple years ago before these people would get their head right and start checking for the real problem which was well outside anything I had control over. Only then, after 10+ tech visits, numerous (20+) calls to Cox and speaking to many supervisors, and ultimately talking to their retention team, was anything done at all.

I have ZERO faith in Cox's ability to quickly resolve upstream issues.

More recently, this year at the end of May for 3 weeks, and then in June for a couple weeks, then in July for about a week off and on, I had the same issues. Cox's termination system at their head end needs to get replaced imo, or they need to hire new engineers that understand how to maintain the equipment.

Within a 3 to 4 year time frame I purchased FIVE new modems to basically prove to Cox there was absolutely nothing wrong with my equipment. In the end it didn't make a difference, all the modems worked just fine.

I suggest you start calling and talking to supervisors and tell them you have brand new equipment that is on their approved list. Make sure the techs have checked everything on the line. Beyond that, it's on them for not providing you with the speed you're paying for. The issues could be a lot of noise on the line from a customer on your node, or could be a problem further up the line. But for some odd reason Cox is loathe to actually do some work to check those things unless you go higher and higher up, waste hours of your time on the phone with them and have multiple fruitless tech visits. After one or possibly two visits to your premises, it's time for them to start talking to their ops team and put a ticket in to check further instead of stringing you along with more ridiculous wasted visits and calls to them. You need to insist on it.

Thank you for your reply! I will do just that. 

I strongly hope I do not need to get to 10 visits and 20+ calls to get to some level of resolution but I have to echo your sentiment in my lack of confidence for Cox to address the issue in a timely fashion. In fact, I thought of cancelling(or at least threatening to cancel in order to motivate someone to actually look into the issue) but the reality is that there is only one cable internet provider in any given area. Not that there aren't other options via lesser technologies but I feel as though at the end of the day I'm stuck at the mercy of Cox and whether or not they choose to address my issue OR getting lucky enough to get a tech who is equipped with both the experience and knowledge to look into the issue at the very least. I will keep pushing. Thanks for the boost of encouragement... it may take many more calls and visits but if I'm persistent maybe we will eventually reach resolution.

The purpose of the Cox Internet Forum is to allow customers to discuss technical topics related to residential Cox Cable, Telephone and High Speed Internet services with other customers. This appears as if you may need for someone to look into your account personally.  We can definitely be able to assist you with this.  Please reach us on Twitter at @CoxHelp, visit us on Facebook, or email by at cox.help@cox.com. Provide us the name on the account with the full service address with a link to this thread so we can get started.

I too am having the same issue. All was fine up to a few weeks ago, or at least I did not notice the issue until I started using a Ring Doorbell and that needs upload speeds of at least 2M, and I pay for the 150/10 and I would expect to at least get the lowest of 1/2 of the 10M at worst case. I have called COX support they have rebooted my Modem and I have just had the Modem for ~14 months. I am so upset that the COX can afford all the promotional on the TV and all the ** in the mail, yet they cannot afford to keep the equipment updated!!! I have a tech coming in a few hours, and I am not looking forward to the interface and having someone tell me it is the Modem again. Since this AM the upload speed was at 10.57Mbps and now it is at less than 1Mbps.