Bait and switch...

If you're already paying the $9.99 gateway rental fee to Cox, then simply go to the store and swap out your gateway for the Arris TG2472. I don't know what area you're in, but here in AZ, Ultimate was upgraded from 150 Mbps to 300 Mbps about 12 months ago.

Or do like many of us do and buy your own equipment. My Netgear Nighthawk router has been going strong for over 3 years now, I only had to upgrade my modem once Ultimate was 300 Mbps.

If you're already paying the $9.99 gateway rental fee to Cox, then simply go to the store and swap out your gateway for the Arris TG2472. I don't know what area you're in, but here in AZ, Ultimate was upgraded from 150 Mbps to 300 Mbps about 12 months ago.

I intend to. The problem is that I've now been paying for something they haven't been providing me with for a year now. The fact that I can get it moving forward doesn't address the issue of what's already occurred. 

Or do like many of us do and buy your own equipment. My Netgear Nighthawk router has been going strong for over 3 years now, I only had to upgrade my modem once Ultimate was 300 Mbps.

My router is already more than sufficient. The problem has been the modem. I have Cox TV, so I got their combination phone/internet modem so I didn't have to employ a splitter. No one said it wasn't sufficient to get the service I was paying for.

Actually the Ultimate tier doubled in speed sometime in the past year.  I know I got a notice when my Premier increased in speed at the same time asking that we ensure we use a modem compatible with the new speeds.  I only noticed the bill insert because I tend to look over all of them to see if there are any new offers.

If you rent your modem, all you need to do is stop by a store to swap it out.

If you own your modem, you have options.  You can purchase one from Cox or any other retailer.  Here is a list of all the modems that are known to work with Cox: http://www.cox.com/residential/support/internet/article.cox?articleId=b2ec95d0-7ef9-11df-5590-000000000000

Choose one that is compatible with either all tiers, or ultimate.

@WraithTDK

As other have suggested it's a simple equipment swap if you have phone service with us. If you wish to continue to use your own router however the TG2472 won't be an option. In that case your best option would be to purchase a stand alone modem with 16 or more downstream channel support.

As other have suggested it's a simple equipment swap if you have phone service with us.

And that will give me back the year I've been paying for speeds I couldn't get because you issued equipment to me that wasn't fully compatible with your service?

"It's easy to fix going forward" doesn't change that it's been a problem for a year, Cox knew it was a problem for a year, and they continued to charge me until they had something more expensive to charge me for. 

If you wish to continue to use your own router however the TG2472 won't be an option. In that case your best option would be to purchase a stand alone modem with 16 or more downstream channel support.

Why? Is the TG247 you rent out locked down? Because normally they can be put into bridge mode rather easily.

@WraithTDK

As for Ultimate and your modem it would have been compatible with the Ultimate speeds that were offered last year. Customer were notified via in browser alerts during a few campaigns during that time recommending that they upgrade equipment. It sounds like those notifications may have been missed.
Our gateways are designed to not be used in bridge mode and are reserved for customers that specifically wish to subscribe to our home networking service.

Setting things up in Bridged mode is a non-trivial act of network setup.  It is incredibly easy when doing this to bork your internet in not easy to figure out ways. 

Having two routers on a single connection is like having two cops directing traffic at the same intersection, but they can't see each other.  ** goes everywhere.

IF, and only IF, you are knowledgeable enough to set up routing, know what a subnet is, how to calculate network masks, then I would say feel free to set up your network however you would like.

Most Cox retail stores have SB618x and SB6190 modems available for purchase/rent unless that has changed.

A+, Network+, Security+ certified, working on Cisco. 15 years in IT,  including five years as admin for the largest real-estate company in Virginia.

I could probably figure out how to put yet another a modem into bridge mode.

I'll buy my own equipment, I don't need to be protected from myself, and I'm not paying an extra nine bucks so I can chose between dealing with two different devices NATing traffic, or give up my $400 routers. I'm not thrilled I wasn't contacted about this. You seriously handled that through "browser alerts?" That's how you tell people about this stuff? Browser alerts? That's assuming an awful lot, isn't it? That people are going to your page? Or running a plugin? Not a week goes by that I don't get fliers in my mailbox trying to sell me cable TV, and when there was a more expensive modem, I got a paper notification for that; but I've been using outdated equipment this long and the only notifications were "some people got browser alerts?" 

wow.