关于OPEVPN模式Replay-window backtrack occurred问题

OPENVPN官方解析是

One possible cause is a link or connection problem, such as high latency on your network link
Another possibility is a conflict with another SSL connection; make sure your VPN tunnel is up and running *before* checking your email, visiting a website that requires SSL, etc.
Exit out of your web browser or email client and try connecting with OpenVPN again

比较有可能的是由于本地网络/服务器网络丢包造成。