I’m currently running OPNsense virtualised in Proxmox. It’s a little confusing if you haven’t run a custom firewall before but the setup was relatively simple and works flawlessly now that I understand it a bit better. The only downside being if you are running it on the same machine as your services and need to restart, your network will go down as well. Ideally I will get another machine just for network services as it sounds like you are doing.