R9000 5GHz visible but cannot connect. 2.6 band is fine

[Twwphd]

Had XBox S and new Samsung UHD 65 connected via 5GHz and had worked fine until a month ago. My Samsung Note5 gets an "authentication error" and fails to connect as well.

The R9000 has the latest firmware and has been rebooted several times.

[ElaineM · Accepted solution]

Try to factory reset the router and see if that will help.

Resetting will wipe out all the settings of the router, so you will need reconfigure it after.

You may want to use backup and restore feature for easy reconfiguration.

[ElaineM]

Have you tried changing the wireless channel?

Will you experience the problem if you downgrade the firmware?

[Twwphd]

I don't know what/how "changing wireless channel" means.

I had problem before I installed latest firmware. 

[Twwphd]

So I figured out how to change the channel-no luck. None of my various devices will connect to the VISIBLE 5GHz band.

[ElaineM · Accepted solution]

Try to factory reset the router and see if that will help.

Resetting will wipe out all the settings of the router, so you will need reconfigure it after.

You may want to use backup and restore feature for easy reconfiguration.

[Twwphd]

Factory reset fixed it. May have been due to 5GHz band being set to wrong security type-just let everything set at default and all bands performing well and all accessible.