LEDE 17.01 5GHz not visible ar71xx WNDR4300

Hi today I switch to LEDE 17.01 final and I experience a strange issue. The 5Ghz is available on all devices except 1 android phone, on my iphone it is visible and I'm conmected. Rebooting the phone did't solve it I really had to reboot the router. I'm using a (ar71xx) Netgear WNDR4300.

Does your android phone support 5Ghz? I have a Samsung J3 and it only support 2.4 Ghz. Or maybe your android device doesn't like DFS channels?

Have you set your country code on your router?

Even if your phone does support the 5 GHz band and DFS in general, it might not be able to tune into all channels allowed in your region and offered by your router. E.g. the frequencies reserved for short range devices (ETSI EN 300 440-1, 5.725-5.875 GHz) were just added to the allowed frequency spectrum a bit over a year ago (with a very low transmit power of 25 mW), many smartphones most likely don't even know about them yet.

@DjiPi @slh Thank you for your responses. The phone is a Samsung A5 2016 and supports 5Ghz. Before LEDE I used OpenWRT with the same channel, same dBm,the region is filled in correct. At this moment it's connected but I experienced the same with the RC's of 17.01 that after a while it's not connected and the weird thing it cannot find it anymore. Maybe it has something to do with the DFS channel because in OpenWRT it was just a normal channel (channel 52, dBM 20). I don't know if it can be something with the Airtime Fairness Patch?

Which channel do you advise to use?

I finally got some logfiles:
Tue Feb 28 19:17:09 2017 daemon.notice hostapd: wlan1: STA 70:28:8b:a6:92:35 IEEE 802.11: did not acknowledge authentication response
Tue Feb 28 19:17:09 2017 daemon.notice hostapd: wlan1: STA 70:28:8b:a6:92:35 IEEE 802.11: did not acknowledge authentication response
Tue Feb 28 19:17:09 2017 daemon.info hostapd: wlan0: STA 70:28:8b:a6:92:35 IEEE 802.11: deauthenticated due to inactivity (timer DEAUTH/REMOVE)
Tue Feb 28 19:17:22 2017 daemon.info hostapd: wlan0: STA 70:28:8b:a6:92:35 IEEE 802.11: authenticated
Tue Feb 28 19:17:22 2017 daemon.info hostapd: wlan0: STA 70:28:8b:a6:92:35 IEEE 802.11: associated (aid 2)

It is trying to connect to 5Ghz, then it didn't acknowledge authentication response, and goes connecting to the 2,4Ghz.
On he phone the 5Ghz is also not visible any more unless I restart the router.

I don't know if it has something to do with this thread:
https://bugs.lede-project.org/index.php?do=details&task_id=34

I hope nbd gets a chance to look at all these 5 Ghz issues. They seem to be piling up on ath devices.

I tested several things: the LEDE 17.01 final, the LEDE 17.01 snapshot, disable the airtime fairness patch all the same result.

The wifi is visible and device connected and at some point it's not visible anymore.

With OpenWRT with the same configuration I don't have this issue.

I'm still investigating what could cause this.

Didn't figure out yet what the problem is, but something in the ath9k driver is causing this problem.

For now I reverted back to OpenWRT as I can use all devices on 5Ghz with that.

@DjiPi @slh It seems something to do like you guys said with DFS.

Newifi Mini with LEDE 17.01.2, same here. 5G signal is not visible to my Android phone(New Moto X, Android 7.1.2), but visible to my Windows laptop.

Do you have the wmm option enabled, e.g.:

option wmm '1'