To connect OpenVPN from iPhone/Adnroid mobile device, some modification of the connection process is needed.
Please reference this forum post from NeoGeek83: http://forum.qnap.com/viewtopic.php?p=318258
To quickly connect your mobile device to a OpenVpn enabled QNAP.
1) Follow the instructions at http://www.qnap.com/index.php?lang=en&sn=4353
2) You have to modify the downloaded file to work. Start by extracting the zip
3) Copy the entire contents of the ca.crt and replace the ca ca.crt line in openvpn.ovpn with:
ca.crt file contents
4) To the end of the file, add a line with (there isn't a user cert for this VPN, just the username/password):
setenv CLIENT_CERT 0
5) Check that the destination host is correct. You should probably setup dynamic DNS at this point if your network doesn't have a static WAN IP.
6) Save and load the openvpn.opvn config file on the phone someplace you can find it.
7) Install OpenVPN on the mobile device
8) Open the App up, select Menu->Import-> Import Profile
9) Select the openvpn.opvn file you created on the phone in step 6
10) It should import successfully. Try to connect, accepting the trust dialog.
11) That's it, you should be connected now. If not, make sure you didn't make a typo in your config file.