Try a 60 second factory pinhole reset as below;
Remove any ethernet cables from the Hub and hold the pinhole reset switch for 60 seconds. Do NOT reboot the Hub, just let it do it's thing. Note you will need the passwords from the bottom of the Hub afterwards, so make sure they are legible.
This will completely refresh the Hub and may allow the app to reconnect.?
There is nothing I can think of that you cannot do with the Hub's admin pages, that you can do with the app. I don't use it btw 😉
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