RT-AX86U "Internet status: disconnected"

[Brianz72]

After six months of flawless performance on fiber, my internet went out overnight. Says "Internet status: disconnected" even though I haven't changed a thing in months. Oddly, performance is still excellent when I speedtest, although it will delay loading some sites for several seconds where it didn't previously. I have attached a couple screenshots of the configuration. Updating firmware just now didn't help. I'm glad it works but there's obviously a configuration problem somewhere.

[RogScott]

That "status" comes from the router periodically making DNS resolution calls for a specific Microsoft hostname and checking the IP addresses returned.

Some firmware versions allow viewing/changing the values (and some versions are hard coded and cannot be viewed/changed). Look on the "Administration, System" tab, under "Basic Config" section, for the following entries (default values shown):
Resolve Hostname: dns.msftncsi.com
Resolved IP Addresses: 131.107.255.255 112.4.20.71 fd3e:4f5a:5b81::1

If you have those fields shown in your firmware version but the values are missing or different than above -- try changing them to the above values. If your version of firmware doesn't expose them, then the best way to reset them to the defaults would be to set the entire router to defaults.

Anything that "breaks" a DNS lookup of hostname dns.msftncsi.com or returns incorrect IP's will cause the status to show "disconnected", even though you are actually connected. For example, if your DNS host doesn't resolve it, or if you are using something like "pihole" or a DNS provider that does ad-blocking via DNS and resolves that hostname to "0.0.0.0" or an adblocking server's IP, then the router will constantly show "disconnected" status.

You can debug using "nslookup" on your computer and seeing if dns.msftncsi.com is resolved properly. If it doesn't resolve to one of the addresses shown above, then that is why the AX86U thinks you are "disconnected".

In some older versions of firmware, you can disable the check entirely. Just above the "Resolved Hostname", look for "Network Monitoring" and disable both options (DNS and Ping), and the router will stop trying to verify "status". But latest versions of firmware don't show any of these options, so you cannot disable it or change the host used. The only solution then is to make sure dns.msftncsi.com can be properly resolved.

[jzchen]

ASUS recommends a reset to defaults after a firmware update. I would try that first:

https://www.asus.com/support/FAQ/1000925#m2

[jzchen]

Strangely there was a .48377 firmware update available last night, then briefly on the ASUS US website this morning, but now it is gone on the website. My RT-AX86U still has it. Hmmm...