Corrupted MAC on input

I just ordered a KS-2 and using a Win 10 Pro putty 0.77 logged in.
The problem I'm having is that I get disconnected from the server randomly and with high frequency. I can experience delayed key strokes just before disconnects, like communication is being interrupted.

From the logs:
> Blockquote
Oct 1 07:46:35 ns333926 sshd[8070]: Corrupted MAC on input.
Oct 1 07:46:35 ns333926 sshd[8070]: ssh_dispatch_run_fatal: Connection from ********* port 60172: message authentication code incorrect
Oct 1 07:46:35 ns333926 sshd[8070]: pam_unix(sshd:session): session closed for user root
> Blockquote

I tried Windows PowerShell, same problem. I think it's a hardware issue because Rescue Mode also does the same thing. I've also tried Fedora, Centos, Ubuntu, Debian fresh installs, and all are experiencing this disconnect.
It's not a keep-alive issue, clearly because it says it's a MAC message authentication code that's corrupted.
I tried disabling offloading by calling "ethtool -K eth0 rx off tx off" but that didn't help.

Any ideas?