> On a remote network I run ethtool on both cards and I got both 1000Mb/s
> speed
>
>
As the 20 odd MB/s you're getting is above what is possible on 100M
ethernet, you can rule out any ethernet interfaces at 100M.

Can you describe the network between the two systems with the slow transfer?

If there is a fast WAN from one side of the globe to the other it could be
latency related. OpenSSH used to have a fixed internal window size that
made it slow on high bandwidth high latency links, and I notice the hpn USE
flag still exists in the openssh ebuild, which implies the issue with
openssh still exists. Rsync can use either ssh or its own protocol, so if
there's a high latency link between the two boxes and rsync is using ssh,
you could investigate rebuilding openssh with +hpn.

What does ping show the latency as?

Otherwise i'd be thinking about packet loss. First place to start for that
is on the endpoint interfaces;
ifconfig enp35s0f0 | grep err
        RX errors 0  dropped 0  overruns 0  frame 0
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0