Download Source: https://openwrt.org/ Current Release is 15.XX
If you are using a Router and want to have a very secure 2nd Firewall you should take a closer look at the openwrt project.
Its free for Download and offers lifetime free Updates and is smooth to handle. Everyone can install it on Routers and learn how
Firewalls are built, what kind of Traffic is send thru the Local Network and which Devices phone secrets home!