Asus RT-N66U OpenVPN TUN config

Hi there,

I have 2x RT-N66U routers setup at different cities. Both now are running 378.55.
I am looking for advice to improve security & performance of my OpenVPN setup.

I used an old guide a year ago (which isn't online anymore) to setup one router as OpenVPN server and the other router as OpenVPN client.
I did not generate a certificate, i just setup the server as this:
http://imgur.com/8yYqVFV

Exported these settings and imported on the other router that is acting as a...

Asus RT-N66U OpenVPN TUN config