ronisaacson:

In the Easy Installation section for the Asus RT-AC58U and related devices:

https://openwrt.org/toh/asus/rt-ac58u#easy_installation

there's a warning that you should backup the wifi calibration data before starting. This links to a thread which talks about the calibration data, but doesn't tell you how to take such a backup.

The backup instructions are here, in the first 6 bullets:

https://forum.openwrt.org/t/how-to-properly-install-openwrt-on-asus-rt-ac58u/44104/7

Maybe the link should be updated, or these instructions should be added directly to the page.