Connection to HA silently lost when switching between WiFi and mobile data network #4045
Description
Running a VPN here that activates on mobile devices when not connected to a specific SSID to make the applications hosted on a secure home network always accessible by IP.
On an older device, since a few builds ago, there is a problem when switching from WiFi to data or opposite: nothing in the HA app can be controlled anymore after the switch until a pull down refresh is performed. This is despite the app acting like being connected and e.g. allowing a brightness slider to be set to a position while the light is not actually adjusted. There is no visual connection error. After a minute, rarely the connection comes back, sometimes an error like "Action ... could not be executed. connection lost", other times nothing happens. It does seem like HA is still able to fetch the location in the background, although this was not thoroughly tested.
On a newer device with older app version, switching between WiFi and data is near seamless. Within 2 seconds the connection is live again and works just as before the switch.
Tried: device soft reset, full app reinstall including relogin, HA restart, messing with the internal/external url and local push.
HA 2025.11.3
Older device:
iOS 16.7.12
iPhone 8 Plus MQ8L2CN/A
HA app 2025.12.1 (2025.1546)
Newer device:
iOS 18.7.2
iPhone 13 Pro Max MLLA3ZD/A
HA app 2025.10.0 (2025.1443)
May I note that the app message as below, is somewhat of a strange experience when running an on-demand VPN.
Your Home Assistant is only accessible on your home network. To control your smart home from anywhere, you can set up remote access later in your settings.