XCP-NG: Throttled NICs?

I’m new to this but trying to run pfSense on an XCP-NG 8.3 box. There are 2x NICs passed into pfSense (1x Realtek 2.5Gb/s + 1x Intel 10Gb/s) and XCP-NG is reporting the ports as connected at 2.5G and 10G respectively. They are bridged in a LAN on pfSense and I’ve put a box running iperf on both ends.

When I run an iperf test, I seem to be getting 1Gb/s through when I was expecting the 2.5Gb/s to saturate and be the limiting factor???

The CPU on the XCP-NG box isn’t pegged. Any ideas?

Most likely an issues with the Realttek NIC, they can be buggy compared to the Intel ones.