How do I prevent TCP connection freezes over an OpenVPN network?
This command solves it for me:
$ sudo ip link set dev tun0 mtu 1350 && echo ":)"
You can Verify tun0 settings with
$ ip a s
Cheers!
Disable Window Scaling in TCP, with:
sysctl -w net.ipv4.tcp_window_scaling=0
After doing that, SSH to Debian/Ubuntu Systems over VPN are working fine for me.