Added 2.5Gb nic only running at 100Mb

Added a basic 2.5gig nic to my machine (HPE DL380 G9) as the built in 1Gb (onboard 4 x 1Gb port) is a bottleneck when moving big files around.

I've updated the mac address so the 2.5 card is the first connection. It shows up on the network and I can read/write to the shares fine but the speed never goes over 100Mb/s. If I use one of the onboard 1Gb port it maxes out to 1Gb/s.

All machines involved have 2.5G nic and the switch is 2.5G.

What did I break?

edit - iperf3 gives full bandwidth both ways. Think my drives are haunted. Solved?