New user: Android companion app: Connection using Nabu URL does not work remotely

Mobile Apps Home Assistant Companion for Android
1

At home on WiFi, HA connects fine. I setup and paid for Nabu so I could have secure remote access, but the HA app on phone cannot connect when away from home WiFi.
Unable to connect to Home Assistant,
…please review the connection settings and try again…
REFRESH EXTERNAL URL does not fix it.
URL on phone is same on dashboard at http://homeassistant.local:8123/config/dashboard using home WiFi
Restart did not fix it.

If I enter the Nabu URL into web browser on the phone, it connects. The problem seems be only with the Android companion app.

2

You need to set your external URL to the nabu cassa remote URL.

In the app:

Settings → Companion App → (your server) → External URL → Switch on Home Assistant Cloud.

Also make sure the Internal URL is set to your local HA server e.g. http://homeassistant.local:8123 though the IP address would be better if you have a static IP address for HA (you should).

Also in the internal URL settings make sure your local wifi SSID is listed.