HubOne not connecting some devices

[#1]

My HubOne has recently (last couple of days) stopped connecting some devices to the wifi in our home.

For the devices that can connect, the internet works fine.

The blue light is on.

At the time of writing:

My iPhone won't connect - my wife's will and she is sat next to me.

Echo Dot in the kitchen won't connect - but the one in the lounge will.

Sony TV lost its connection whilst paused on BBC iPlayer. Now won't connect by WPS or manual entry of password.

All the non-connecting devices have previously connected perfectly and repeatedly without any issues.

They have all stopped connecting when not being actively used. By that I mean I wasn't pressing buttons on them or knowingly asking them to do something.

They can all see the network, but won't connect.

I've turned everything off and on again.

What technical info or tests do I need to do for someone to identify (and fix!) the problem?

[#2 · Accepted solution]

I fixed it by unplugging a wifi-extender.

No idea why some devices worked but others didn't, or why they suddenly stopped working and wouldn't reconnect.

But removing the wifi-extender seems too have removed the problem.

Kind of frustrating, because the wifi extender is supposed to improve the wifi coverage, not impair it.

[#3]

You might want to try factory resetting that WiFi extender. Set it up again from scratch. It may stop it from interfering with your connection.