But since today I’m not anymore able to connect, as soon as my iPhone is connected to my Wi-Fi. I even tried to change the settings, and to force using the duckdns address in all cases, still not OK. Idem if I try using the local IP address.
It is working when I switch off my Wi-Fi connection on my iPhone, but I’d obviously like to use my Wi-Fi network as much as I can.
Something even more strange: using the local address or the local IP in a browser works very well, I can then access my HA, from my iPhone connected to my Wi-Fi.
I managed to connect to my HA ! For a reason I still need to investigate, by activating my VPN and forcing using the duckdns url, I can connect to my HA even if my mobile is connected to my WiFi.
Since it works with a browser on your phone, it seems to be related to the companion app.
You might change your OP by adding the companion app as the category.