I recently bought an Asus router RT-AC68U to flash Tomato firmware as AirVPN offers a config generation for this. I had a few issues with that and noticed that Asus supports OpenVPN from scratch. I've tried it and it works flawless, no tomato is needed.
Difficulty: Very low
Time: 2 Minutes
- Asus Router (in my case it's a RT-AC68U but it should work for all asus routers that have OpenVPN support)
1. Browse to https://airvpn.org/generator/ and select 'Router or others' and choose a server you like. Tick on 'Direct, protocol UDP, port 443' and click on 'Generate'. Save this openvpn config file anywhere on your computer.
2. Open the asus router webinterface and click on 'VPN'. Click on 'Add profile', choose OpenVPN. Enter a description, leave username and password EMPTY. Click on 'Browse' and select the downloaded openvpn config file. Click on upload. Click on OK. That's it now you can click on connect.
3. Visit https://ipleak.net and check if it works.
By default I have no dns leak. But in case you have you can setup the AirVPN DNS this way:
3b. Click on WAN tab. Turn DNS server off and enter either google's DNS 220.127.116.11 or AirVPN's DNS 10.4.0.1 or both as in the screenshot.
That's it. Every client which is connected to the router now is secured by VPN.