something that can push at least 2-3 4K streams.
12th gen i5 with 16GB DDR4. Maybe 32GB if I can swing it.
unless you're transcoding each stream that should work, at least for Plex.
Currently running 10th gen i5 with 32gb of DDR and can run one 4k transcode, five 1080 streams, and four live TV streams. though, the transcode is laggy but if you pause and let it buffer it should work.
keep in mind I'm also running headless transmission, a VPN, tor, and like 8 other services on the same server.
if all you're streaming is 4k, you will hit a point of diminishing returns on network throughput. I'd recommend getting a switch with SFPs and connect your server up to a 2.5gbe or even a 10gbe (though overkill but the sky is the limit). as long as all your stream boxes are connected through that switch on their regular 1gbe they should be fine.
personally I run a opnsense router/firewall and have everything passed through an unlocked Brocade ICX6610-48P-E. you can find them on eBay. FYI, these are commercial units and are VERY LOUD. basement or attic installation is a must if you don't have a network closet. bonus, the ICX6610 allows you to turn on/off POE per port and even set the voltage. this means you can power everything from cameras, stream boxes, wireless APs, to even some POE lights. it's also a managed switch, which means you can split your ports up on VLANs and other really neat things.
