OpenWRT Firmware

Wifi is generally kinda hard to troubleshoot, but you could try to set the "log_level" to 0 to maybe have some better hints in the logs. I could also tell you to look at your transmit power, but I assume you've already done that and that's not something that should change with time anyway.

Hi Wasa!

Sounds like it could potentially be hardware related, have you set openwrt to default settings at all? Typical question, but it'll rule out hardware if it suddenly works again... Keep a USB with OPENWRT fresh if you want to diagnose things sometimes. :)

I've seen issues with the country codes causing instability if the wifi chip is defined for a specific set (unlikely). If not, view the wifi graph potentially to look at your signal to noise ratio, it's not very accurate as you can imagine, but something out of whack may show.

Another bet may be to check for any USB settings in the bios potentially - I don't personally own that NUC but I do know changing the USB to 2.0 may resolve some issues; if the wifi card is lower than the bandwidth of USB of course.

Maybe check the antenna connections? Have you got a photo to show how you installed them, there may be an issue there.

You can consider this if you wish to observe the bands and actually determine any inteference: https://www.bastibl.net/ath9k-spectrum-scanning/

There's other values that djtambor mentioned that could help too!

Post more details about the hardware you're using. What wifi chip, driver, so on are you using? :) Best of luck!