pfSense is a free and open source firewall and router that also features unified threat management, load balancing, multi-WAN, and more.
I have been using pfSense for about 4 years now, and have to say that I love it. The one thing that I had always been concerned about was running out of IP addresses once my VMs (Virtual Machines) got too large or too large to handle the default 192.168.2.0, which is only 254 IP Addresses. So, that would take up around 200+ VMs. With pfSense, I was able to set up a subnet mask /16 network (CIDR notation), which corresponds to the dotted-decimal subnet mask 255.255.0.0. Allowing for 65,534 usable IP Addresses.
In your network settings, you would do something like this.
TrueNas Scale