Why can I get on <1G on my 10G Network?

I have 4 CentOS 7 boxes with SuperMico 10000BaseT NICs plugged into a Netgear ProSafe XS712T switch with Cat8 cables. Switch is all default settings, but shows NICs at 10G Full. NICs are configured:

(root@VH11 ~)# ethtool ens1f0
Settings for ens1f0:
        Supported ports: ( TP )
        Supported link modes:   100baseT/Full
                                1000baseT/Full
                                10000baseT/Full
        Supported pause frame use: Symmetric
        Supports auto-negotiation: Yes
        Supported FEC modes: Not reported
        Advertised link modes:  10000baseT/Full
        Advertised pause frame use: Symmetric
        Advertised auto-negotiation: Yes
        Advertised FEC modes: Not reported
        Speed: 10000Mb/s
        Duplex: Full
        Port: Twisted Pair
        PHYAD: 0
        Transceiver: internal
        Auto-negotiation: on
        MDI-X: Unknown
        Supports Wake-on: d
        Wake-on: d
        Current message level: 0x00000007 (7)
                               drv probe link
        Link detected: yes

There are ONLY 10G NICs plugged into the switch.

I can only get transfer speeds of less than 1G on file transfers as reported by rsync, scp and iftop when transfering 1 20G file. When I test from server > switch > server with iperf, it tells me it gets 9.38 Gbits/sec, but I only get 10% of that on file transfers with rsync or scp.

What am I doing wrong here?

Thanks in advance for your time.