I’m a fan of pfSense, myself. But other suggestions here for OSes have been reasonable. I have a netgate router feeding an eero wap with a second wap creating a bridged wifi network. Future-proofing with 10GB on a wired switch if a good idea. I got a Unifi 2.5GB switch with 10GB uplink for that. The difference in performance moving large data around is massive. I have 10GB between my primary machine, the one that I run as my always-on server, and my NAS. It’s awesome. Everything else is 2.5GB.