VLANs, not using switches, adding extra NICs

[Velociraptor]

I'm going to use Opnsense to replace the router my ISP provides, so I've bought a nice SFF machine and I have Opnsense installed. I'm waiting until I have 2 consecutive days off before I make the big change in case something goes wrong since I'm working from home.

Since there will be the PC I'm going to use for Opnsense, and a FreeNAS server always on I had the idea of adding cheap NICs from ebay to them to add additional ethernet ports to my network. I do have a 24 port switch but it's almost full.

However the friend who recommended Opnsense has advised to be cautious with this and that it will mean setting up VLANs to get them in, will mean a complicated configuration and potentially cause problems further down the line if I make changes to the network.

When I've looked for explanations on what VLANs are etc I come across documentation that starts by explainsing why I want a VLAN. I don't really want a VLAN, ideally I'd like everything all together but I don't believe that's possible.

I don't imagine I'm alone in thinking about doing this so I'm hoping someone can point me in the direction of some kind of resource where I can properly read and understand what's involved so I can get it set up, or conclude it's too much hassle.

[bartjsmit]

You need a managed switch to use VLAN's, but they are easy enough to configure: https://www.theregister.co.uk/2017/06/30/vlans_at_20/

As an alternative, you can run a crossover cable between the firewall and the NAS: https://en.wikipedia.org/wiki/Ethernet_crossover_cable but you may get issues with speed and media state sensing.

Bart...