I've just reinstalled OpenVPN onto a new server, running same hardware, just different OS, ubuntu 12.04.2 to centos 6.4, same hosting facility etc. Ping to the server is about ~110ms and get a good 11+Mb/s over FTP, though through the VPN its taking in excess of 30 secs just to load a page. The server is pretty much idle in terms of CPU/RAM usage, no spikes when trying to load a page etc.
Digging into it, it would seem this is possibly an issue with IPv6/4 dualstack. IPv6 only pages (ipv6.google.com) load instantly, whereas dualstack or ipv4 only pages take ages to load, or dont load at all. Seems to be luck of the draw as to if they load or not.
This is the only error im seeing in the server log
wader/<ip>:57448 Bad LZO decompression header byte: 0
Client config
client
dev tun
proto udp
remote <snip>
resolv-retry infinite
nobind
persist-key
persist-tun
comp-lzo
fragment 1400
verb 3
ca C:\\Program\ Files\\OpenVPN\\config\\ca.crt
cert C:\\Program\ Files\\OpenVPN\\config\\wader.crt
key C:\\Program\ Files\\OpenVPN\\config\\wader.key
Server config
local <snip>
port <snip>
;proto tcp
proto udp
;dev tap
dev tun
ca ca.crt
cert server.crt
key server.key # This file should be kept secret
dh dh2048.pem
server 10.8.0.0 255.255.255.0
ifconfig-pool-persist ipp.txt
push "redirect-gateway def1 bypass-dhcp"
push "dhcp-option DNS 8.8.8.8"
push "dhcp-option DNS 8.8.4.4"
keepalive 10 120
comp-lzo
user nobody
group nobody
persist-key
persist-tun
status openvpn-status.log
log openvpn.log
verb 3
mute 20
