After having months and months of problems with Roon, that seemed unsolvable… I decided to redo my entire home network. I’ve now bridged the incoming Internet connection (access point) to one single router (TPLink Archer, 2022 model), and built up a very simple network from there. And what happened was both astounding and underwhelming… it all just works perfectly. No more CPU hogging, no more skipping (at least not that I’ve noticed), no more problems.
Things on my network: Mobile devices (3 phones, 1 iPad), 3 laptops (2 MacOS, 1 Windows), 2 Windows PCs, 1 Linux Machine (Ubuntu), 2 Desktop Macs (one is the Roon core, both are hardwired).