What's the model of these Google devices? You need to make sure if they support 5G radio. Maybe you can try to connect with 5G radio of other AP/Router, check if these Google devices can work with the 5G radio.

Thanks. They are Chromecast Audio and 2nd gen Chromecast devices so do support 5GHz. I just tested them with another AP (Fritzbox) and they connected successfully.

Eg 

OK. Half a solution. I fixed the 5GHZ channel to the one that just worked on the other router and it connected. This seems to be the issue:

https://www.reddit.com/r/Chromecast/comments/6lwrix/chromecast_2_doesnt_support_high_channels_on_5ghz/

I'd rather not hardcode the channel, but I guess it's one option.

gabrielhopkins wrote

Thanks. They are Chromecast Audio and 2nd gen Chromecast devices so do support 5GHz. I just tested them with another AP (Fritzbox) and they connected successfully.

 

Eg 

263 / 54

5 GHz / ac / 80 MHz WPA2, 1 x 1

 

 

gabrielhopkins wrote

OK. Half a solution. I fixed the 5GHZ channel to the one that just worked on the other router and it connected. This seems to be the issue:

https://www.reddit.com/r/Chromecast/comments/6lwrix/chromecast_2_doesnt_support_high_channels_on_5ghz/

 

I'd rather not hardcode the channel, but I guess it's one option.

gabrielhopkins wrote

Thanks. They are Chromecast Audio and 2nd gen Chromecast devices so do support 5GHz. I just tested them with another AP (Fritzbox) and they connected successfully.

 

Eg 

263 / 54

5 GHz / ac / 80 MHz WPA2, 1 x 1

 

 

 

I figured it out. I have a couple of US EAP225s running on a European network - so all my own fault - but solvable by setting the channels. If anyone knows a way to flash the US controllers with the EU firmware - warranty invalidating or not - I'd be keen to give that a try.