Coax Internet Cable: If I have to build one, what am I looking for exactly?

I have had excellent results using a F-Type ground loop isolation, like this one below:

https://www.amazon.com/Ground-Loop-Isolator-Transformer-Eliminator/dp/B08FRGH4X2/ref=sr_1_17_sspa

It's different than the filter mentioned above.  I think the filter above uses Ferrite magnet filters which the conductor is looped through.

The link I posted is really an isolation transformer for the cable box.  I like it because it screws directly onto your cable modem or receiver.  You don't need two separate cables to place the filter inline.  This has significantly improved both audio and video quality.  However, it may not work in some equipment, especially if the equipment requires two-way communications.  It's cheap enough to try and you can take it out if you get internet connection problems or other weird things.

I couldn’t wait for Spotify HiFi any longer, so I picked back up a Qobuz sub, and I also picked up a Roon sub over the weekend. This is my first time using Roon, and I wish I had been using it for the last couple years. It’s a nice interface. Roon also did a good job simplifying the task of hosting a local server (the Roon Core), which I put on the laptop. Anyway, Roon is a different discussion.

As far as sound quality goes, I am happy with the sound again, playing losses files. But I’m not sure I can say the sound is better, or even much different, than what I had prior. With about a 1-1.5 months since I last played lossless files via Qobuz, I think there was too much time in-between to judge. Plus, I’m dealing with at least a few variables in addition to the new coax cable--namely, the modem and other equipment are now sitting on home-brew isolation boards, and I’m playing Qobuz over Roon rather than BubbleUPNP. At some point, I may A-B test Roon and Bubble to see if I can hear a difference since that’s simple to A-B test. I’ll wait to A-B test the coax cable replacement, which sits between the wall and the modem, once I get more time on the new copper core cable. If I do end up hearing a difference between coax cables, I may consider replacing the coax cable in the attic too. We'll see. 

Phat Satellite coax cable mentioned by @jea48 definitely has a lower noise floor than xfinity coax.

But it was too edgy for me.

I’m streaming with Qobuz.

@macdude I was using the Phat Satellite cable for the last couple years. I switched over to the Blue Jeans RF cable this year along with an AudioQuest RF cable that's not currently in the AQ catalog, and I liked the results.

As a disclaimer, I didn't hold variables constant. I pulled out 4 coax cables in total, one of which was the Phat, and replaced them with 1 AQ and 3 Blue Jeans cables. In sum, I liked the outcome, but I didn't compare 1 Phat vs 1 Blue Jeans directly. 

I have the DH labs coaxial cable for my Xfinity modem.

Has anyone upgraded their Xfinity cable to DH labs?

So far it's one of those "never look back" upgrades.

Wow, just wow. Who would've thought the cable from the wall was the bottleneck?

Just goes to show you how inadequate the Xfinity cable is for music streaming.

Thank you to @auxinput for recommending this cable.