PCI passthrough available?

I have just picked up an UP Squared with a Celeron N3350 CPU and installed Proxmox on it, which works fine, but I cannot enable PCI Passthrough for the ethernet controllers, it says IOMMU is not available (my aim is to run Pfsense directly using the NICs). I have enabled virtualization support in the BIOS - does this board support this feature at all and if so, what else I might need to enable it?