symptoms under loads:
[84579.236440] sky2 0000:01:00.0: error interrupt status=0x40000008
[84579.268416] sky2 0000:01:00.0 enp1s0: rx error, status 0x7ffc0001 length 132
$ iptables -A FORWARD -o enp1s0 -p tcp --tcp-flags SYN,RST SYN -j TCPMSS --set-mss 1492
$ nano /etc/network/interfaces
iface enp1s0 inet static
mtu 1492
$ ifconfig enp1s0 mtu 1492