2019 Mac Pro 10GB Ethernet limited to 1.10GBytes Transfer, 944MBits/sec bandwidth

I have a 2019 Mac Pro (Sonoma 14.2.1) that is plugged into a 10GB ethernet switch. The other end is also plugged into a 10GB switch. No matter which direction, iPerf3 is reporting that I'm only getting 1.10Gbits Transfer and 943Mbits/sec bandwidth. I have confirmed the switches are working as iPerf reports ~7Gbits/sec between two other servers. I have disabled all ethernet and wifi connections except the one I'm testing. I have ensured Jumbo Frames were enabled on the local switch (I also tried another local switch that is 10GB only). I have ensured Jumbo (9000) is selected on the interface MTU. I have tried both AVB/EAV mode enabled and disabled. I have ensured all cables are Cat6+ The speed is recognized as 10GB when set to auto (but when set to auto, MTU stays at 1500, so the rest of the testing has been done with interface set to Manual, 10Gbase-T, full-duplex, Jumbo(9000) MTU). No proxies or QOS or VLAN's or anything fancy. Limit IP address tracking is disabled. Same speed whether running iperf client or server on Mac. The other end I'm testing on are a couple of CentOS boxes. The 2 centos boxes are seeing 10GB speeds between themselves and are passing through the other 10GB switch. Any ideas what could be causing this issue? I had gotten 10GB speeds in the past but moved stuff around and just reconnected the 10GB stuff this morning. I have used a Cisco CBS250-48T-4x which had Jumbo Frames enabled on the 10GB SPF+ ports and saw the connection as 10GB. I'm also testing with a Ubiquiti USW-Aggregation which is 10GB-only. The other end is a Meraki MS425-16 which is 10GB/40GB (plugged into at 10G port) which is auto-negotiation the port at 10GB.