OpenVPN을 실행시 "Could not determine IPv4/IPv6 protocol. Using AF_INET6"와 같은 경고가 표시될 수 있습니다. 현재 서버에서 ipv6를 사용하지 않으니 proto udp를 proto udp4로 변경하여 ipv4로 동작하도록 하면 됩니다. 이 설정값은 server.ovpn에서 변경할 수 있습니다. 아래 코드의 마지막줄에 설정을 변경하세요.

#################################################
# Sample OpenVPN 2.0 config file for            #
# multi-client server.                          #
#                                               #
# This file is for the server side              #
# of a many-clients <-> one-server              #
# OpenVPN configuration.                        #
#                                               #
# OpenVPN also supports                         #
# single-machine <-> single-machine             #
# configurations (See the Examples page         #
# on the web site for more info).               #
#                                               #
# This config should work on Windows            #
# or Linux/BSD systems.  Remember on            #
# Windows to quote pathnames and use            #
# double backslashes, e.g.:                     #
# "C:\\Program Files\\OpenVPN\\config\\foo.key" #
#                                               #
# Comments are preceded with '#' or ';'         #
#################################################

# Which local IP address should OpenVPN
# listen on? (optional)
;local a.b.c.d

# Which TCP/UDP port should OpenVPN listen on?
# If you want to run multiple OpenVPN instances
# on the same machine, use a different port
# number for each one.  You will need to
# open up this port on your firewall.
port 1194

# TCP or UDP server?
;proto tcp
;proto udp
proto udp4