One thing I’ve thought about, but haven’t yet tried, is breaking down the router into its separate components. As you may know, ISPs will supply consumers with all-in-one modem-routers. Lay people who tinker with their home network will usually get as far as breaking down the AIO modem-router into into separate modem and router. But, the router itself can be broken down into another 3 components: routing, switching, and wifi access points. The benefit to breaking these down is network performance--an old computer with routing software installed is going to outperform an off-the-self router from Best Buy--and components can be upgraded separately. Now that consumer mesh router systems are starting to cost upwards of $700, separating out routing from access point management might make sense from a cost perspective too. Anyway, I don’t know of any audiophiles exploring possible sound quality improvements with commercial-grade or DYI networking solutions. But you could create an amazing home network in the process at least.
I have just started to play with Roon Cores/music servers. It seems to me that in as far as the a music stream passes through a router, access point, or switch, that those components may audibly affect the stream.