ath10k FAQ

Why I cannot start an AP in an 80 MHz channel / in 11ac mode?

If you get "nl80211: Failed to set channel" error from hostapd, most likely that means that regulatory database doesn't support 80 MHz channels (which were introduced in 11ac). You can check that with iw:

$ iw reg get
country FI: DFS-ETSI
        (2402 - 2482 @ 40), (N/A, 20)
        (5170 - 5250 @ 80), (N/A, 20)
        (5250 - 5330 @ 80), (N/A, 20), DFS
        (5490 - 5710 @ 80), (N/A, 27), DFS
        (57240 - 65880 @ 2160), (N/A, 40), NO-OUTDOOR

If you do not see "@ 80" within the frequency range you are using, it means that the regulatory database doesn't support 80 MHz channels.

Why my MAC address is 00:03:07:12:34:56?

Most likely a problem with the calibration data or firmware does not support the board in question. Try updating the firmware first.

How can I run latest ath10k on older kernels?

Use backports project.

How do I update the firmware?

See firmware.