A while ago, I ran into the following error message when I tried to update the firmware on my Asus RT-AC66U router.
The router cannot connect to ASUS server to check for the firmware update. After reconnecting to the Internet, go back to this page and click Check to check for the latest firmware updates.
It took me a while to figure out what was going on, so I thought I’d post it here in case anyone else runs into this.
The error message is pretty generic, but in my case it turned out to be caused by a faulty setting on the “WAN -> Internet Connection” screen.
Apparently, I once set the DNS servers manually, then later removed the values, but forgot to set “Connect to DNS Server automatically” to “yes”.
It’s a little weird that Asus’s firmware accepts these settings, because without a DNS server, the router itself will not be able to access the internet properly. Clients will be fine if DNS servers are present in the LAN DHCP settings.
To fix this, either select “yes” to automatically connect to your ISP’s DNS servers, or specify your favorite servers.
Hope this helps.