you can manually download and install the latest firmware always from the ASUS support page RT-AC68U .
It is always better to update the firmware as soon as the new version arrives. i.e you can connect two different ISP connection to the same router.
for example, you can configure your laptop connected to your local network to use the primary WAN and the smart phone to use the secondary WAN always.
when you choose this option, you get additional option to route requests through either primary or secondary WANs.
In this post I am going to walk you through dual WAN router settings.
I am not going to cover the basic WAN settings as there are lot of posts which tells you hot to do it and also the Quick Settings wizard helps to easily set the router up and running for you.
I configured my old adsl modem in bridge mode and connected my modem's LAN output as Secondary WAN to RT-AC68U.
There are two options with which you can enable the dual wan Fail over mode - When the Primary WAN internet connection fails, the Secondary WAN kicks in and provides you with the uninterrupted internet connection (actually there is 30 - 60 secs delay before the Secondary WAN kicks in).
It has been three months since I started using ASUS RT-AC68U as my home router.
I have set up DUAL WAN, Port forwarding, DDNS , Ai Disc and Ai Cloud features.
you can see both the Primary WAN and Secondary WAN are connected now.
you can check if it is working by manually plugging out the Primary WAN cable and wait for sometime. After a while you will see both Primary and Secondary as connected.
In this blog post, I am going to cover DUAL WAN which I like the most.