I was able to get one server to higher speeds by disabling the MTU=1500 option, which leads me to believe there is some kind of packet processing bug. Can you try disabling that option if you can and see if it makes any difference? However the proble...
openvpn results in 92% download speed reduction (40 Mbps vs 500 Mbps)
Today is the first day I've had Rogers service and noticed that any of my devices connected via openvpn would drop in speed down to a max of 40 Mbps after a few minutes of usage...