I run a custom made freebsd pfsense box, before that it was linux with iptables.
For the iptables box, I put a second 4 port intel pro 1000 nic in my normal host, ran a VM with PCI pass through so the VM controlled the nic and used that as a router.
I think there are purpose built routers out there that will do this but it will depend on the router on how you set this up. You'd have to do research on this. Pretty sure the ubiquity routers will let you do things like this. I've done similar on open-wrt.
For the iptables box, I put a second 4 port intel pro 1000 nic in my normal host, ran a VM with PCI pass through so the VM controlled the nic and used that as a router.
I think there are purpose built routers out there that will do this but it will depend on the router on how you set this up. You'd have to do research on this. Pretty sure the ubiquity routers will let you do things like this. I've done similar on open-wrt.