It looks like a corrupt ASD file was the cause of the issue, which caused the routers to run out of filesystem space and memory, eventually crashing (via Ars Technica). This is an update that occurs automatically in a bid to keep routers secure, whether automatic updates are enabled or not.
The company has since confirmed “an error in the configuration of [its] server settings file, which could potentially cause an interruption in network connectivity on part of the routers.”
Asus router fix
Routine security maintenance brought the issue to Asus technical workers’ attentions.
“Our technical team has urgently addressed the server issue and impacted routers should return to normal operation,” it said.
Routers that are yet to have sorted themselves out should be able to do so with a quick reboot.
Users who are still experiencing issues are being told to save the settings file before factory resetting their devices and re-uploading their settings (via an instructions page), or simply hard resetting and setting up as new.
During the outage, one Reddit user found that resetting the router and clearing the NVRAM worked, and while interrupted access to the Internet may have proven catastrophic to some remote workers, Ars Technica reports that the fix was issued within 48 hours, marking the company’s speedy commitment to getting things right and keeping the wheels in motion.