Lost internet and Homey

Question
has anyone an idea how to connect to your Homey in your local home network after pulling out the connection to the global internet ?

The mobile app should fall back to a local connection automatically, at least according to Athom, but experience says otherwise.

You can ask Athom about it themselves: https://support.homey.app/hc/en-us/articles/360015784034-Submitting-a-support-request