Home Assistant - certificate invalid after upgrade - just for iPadOS

Hello.
Have tried to get my head around an issue with the Home Assistant Companion for Apple for some time now.
Running a Home Assistant server (Core 2025.7.1 Supervisor 2025.06.2 Operating System 15.2) on Oracle Virtual Box.
As addon the server runs DuckDNS-service with Let’s Encrypt support
Have several clients running the Home Assistant Companion for Android, but also in Windows.
Also have three clients (iPad) running Home Assistant Companion for Apple. The issue always and only occurs with the iPads.
After the latest update (Core 2025.7.0), once again the three iPads says:
“The certificate for this server is invalid.
You might be connecting to a server that is pretending to be “192.168.x.x” which could put your confidential information at risk”

The solution is easy, just remove the old server in the client-settings and manually add the server again (with the internal and external URL settings as before) and everything works again.

This time, however, I chose to do this only on one of clients (iPad) and again everything worked.
The other two, I chose to leave, all in order to try to understand the reason this issue arise.
I have tried to follow all different suggestion posted, from restart of server and client, over reconnect of network…all without result.

Maybe someone, with wider experience, can support me in order to troubleshoot this issue in the right way.
I imagine that there should be more that have encountered this issue.

Many thanks in advance