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

Thanks everyone. I went with @jea48 's cable recommendation in the first message: PHAT SATELLITE's solid copper core quad shielded. It was very affordable. In the future, I may play around with pricer cables here, but for now, I'm just eliminating bottlenecks. 

My purpose of looking into internet coax cables in the first place was because I wanted to hide the modem behind the furniture where it couldn't been seen. I made a simple isolation platform composed of a nice looking wood cutting board and some isolation feet by Hudson HiFi. Living room looks just a little nicer without the blinking black box visible (see my profile pic). 

Unfortunately, I can't tell whether the tweaks to the system sounds any different because I let my Qobuz sub go thinking Spotify HiFi would have been out by now. Because the tunes are all lossy, I can't say how meaningful the tweaks have been. 

One thought on streaming from the cloud: it seems plausible that having an internet coax cable with at least a solid copper core and some shielding would make a difference for A/V equipment. But I haven't heard any talk about this from digital HiFi reviewers/influencers. Just like having a dedicated power line is something more and more people are recommending, wiring the house with a coax cable containing a solid copper core could become gospel one day for good digital hygiene. 

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.