firewall - Setting up Ubuntu Router - Server Fault
Amazon.com: Qotom Qotom-Q555G6-S05 Mini PC Core i5 7200U Server 6 Intel NIC AES-NI Dual Core Support Linux Ubuntu Gateway Firewall Router Fanless Mini Computer (8G DDR4 RAM + 256G MSATA SSD) :
How to Configure Ubuntu as Router | Do It Yourself
Configure Ubuntu 20.04 as Linux Router - kifarunix.com