That's what I have here. I have a Qotom mini PC, with i5 CPU, 4 GB RAM
64 GB SSD and 4 1 GB Ethernet ports. I run pfSense on it and have a
managed 8 port Cisco switch. Works very well.
No router?
I just described it. A computer, running pfSense is my
firewall/router and it's far more capable than any consumer router
you're likely to buy. I have it configured with my main LAN, a VLAN
for guest WiFi, test LAN and a connection to my Cisco router. I
also have a DNS resolver and NTP server on it and that's just
getting started on what it's capable of. It can even do routing
protocols, such as OSPF and BGP, which can be used between large
networks. In addition to a single IPv4 address, which uses NAT for
LAN, I have a /56 IPv6 prefix, which I can split into 256 /64s, each
of which contain 2^64 addresses. I also have OpenVPN running.