@JBondo 

So you have SmartConnect / Band Steering enabled on the router?  Some device dont like this and will drop out, try disabling this if you do

Also I would consider changing your encryption on the router to WPA2 alone (not WPA/WPA2) as WPA is now becoming legacy.    I know IOS device for example dont like WPA/WPA2 mode used. 

Also have you tried different channels for the WiFi incase its losing signal?   

When you tested it connected to the IPhone, was the IPhone closer to the nest or placed where the router sits?

@Philbert 

Thanks for getting back to me.

I don't have SmartConnect ot Band Steering features on my router (Archer VR2800 / AC2800)

For encryption, there is no option for WPA2 alone, just WPA/WPA2 Personnel, WPA/WPA2 Enterprise, WEP

I've not tried different WiFi channels, so I will try that.

The iPhone I have tried in a few places. I put the iPhone directly underneath the nest so it had full signal, I then put it in the top floor bathroom (3 floors), most furthest away from the Nest which only reported 3 bars of signal (out of 5), the nest was still happy connecting to the iPhone. I thought signal could be the issue as the router only shows as 3 bars but the iphone on the top floor debunked that idea!

Edit:

Nest is currently connecting to 5.0Ghz network, have changed it to Channel 36 with Width set to auto. No success still flickers offline

Changing WiFi to 802.11n only for example has not worked. I've tried doing this with the 5.0Ghz network too but nest does not connect.

Hi,

Just to follow up with this... It turns out the issue was actually our ISP. Kept dropping out etc, we've since changed and no problems!

@JBondo 

Ah ok that would explain it! 

Glad you got sorted ok :)