We are a small business. I am running pfSense on a decommissioned developer's PC. We have also a Cisco SG 300 L3 switch, capable of VLANs and LAGG (link aggregation).

I am going to do RoaS (router on a stick) with 3 - 4 VLANs and a firewall between them.

The PC that is being used as a router has 2 integrated NICs and 4 available PCI slots. All links are 1Gb.

I want to avoid congestion so I am planning to buy 4 additional PCI network cards and use either LAGG or put different VLANs directly to different NICs on the router.

Which one is better?

If I go the LAGG way, which mode is best - LACP or LOADBALLANCE?

Thanks.