the question of changing ethernet cables

What is the problem that is being solved?
How does it manifest itself in the sound?

You are correct on noise coming into house, however self generated noise and jitter from modem on still exist in all streaming setups. Whether you need a filter or not is for you to discover via experimentation. I've done much experimentation with streaming setups over the years, sometimes there is progress other times regression, and sometimes change is just change. Streaming can be as simple or complex as we choose it to be, curiosity certainly has hold on me!

I purchased a Shunyata Sigma Ethernet cable that goes from the wall to my streamer.  It made a positive difference. I purchased an open box, so somebody didn’t keep the cable, so make sure that you have the ability to return the cable.

There are many comments here that fibre avoids EMI/RFI conversion altogether. Conversely some very experienced members prefer Ethernet avoiding the media conversion to fibre. I concur with @sns that any streaming solution is unique, depending among others on the quality of the incoming signal, quality of modem and router as well as their power supplies, EMI/RFI intensity of the location, quality of the cables as well as the receiving port implementation, noise rejection quality of server and dac and and and…l

In my experience using isolators on both Ethernet and USB resulted in significant quality improvement, that said YMMV

Unless you’re running fiber from your ‘box’ to ps audio streamer, you’re still susceptible to noise. In your setup, your router is a potential source of noise. Are you using a wall wart (another source of noise) or linear power supply to power the router? As suggested by @antigrunge2, use a network isolator ahead of PS Audio. Listen, access and share your thoughts.