Network design. I started my homelab / selfhost journey about a year ago. Network design was the topic that scared me most. To challenge myself, and to learn about it, I bought myself a decent firewall box with 4 x 2.5G NICs. I installed OPNsense on it, following various guides. I setup my 3 LAN ports as a network bridge to connect my PC, NAS and server. I set the filtering to be applied between these different NICs, as to learn more about the behavior of the different services. If I want to access anything on my server from my PC, there needs to be a rule allowing it. All other trafic is blocked. This setup works great so far an I'm really happy with it.

Here is where I ran into problems. I installed Proxmox on my server and am in the process of migrating all my services from my NAS over there. I thought that all trafic from a VM in Proxmox would go this route: first VM --> OPNsense --> other VM. Then, I could apply the appropriate firewall rules. This however, doesnt seem to be the case. From what I've learned, VMs in Proxmox can communicate freely with each other by default. I don't want this.

From my research, I found different ideas and opposing solutions. This is where I could use some guidance.

1. Use VLANs to segregate the VMs from each other. Each VLAN gets a different subnet.
2. Use the Proxmox firewall to prevent communication between VMs. I'd rather avoid this, so I don't have to apply firewall rules twice. I could also install another OPNsense VM and use that, but same thing.
3. Give up on filtering traffic between my PC, NAS and server. I trust all those devices, so it wouldn't be the end of the world. I just wanted the most secure setup I could do with my current knowledge.

Is there any way to just force the VM traffic through my OPNsense firewall? I thought this would be easy, but couldn't find anything or just very confusing ideas.

I also have a second question. I followed TechnoTim to setup Treafik and use my local DNS and wildcard certificates. Now, I can reach my services using service.local.example.com, which I think is neat. However, in order to do this, it was suggested to use one docker network called proxy. Each service would be assigned this network and Traefik uses lables to setup the routes. ' Would't this allow all those services to communciate freely? Normally, each container has it's own network and docker uses iptables to isolate them from each other. Is this still the way to go? I'm a bit overwhelmed by all those options.

Is my setup overkill? I'd love to hear what you guys think! Thank you so much!