I have a similar problem with PiHelper. That is an iOS app which is connecting to the Raspberry Pi via SSH and reading telemetry, and can reboot the device, etc. It can connect my RPi2 which is running Volumio with no issues, but the connection fails when I try to connect to RPi4 with Libreelec 11.0.6. It's setup the same way as my terminal which is able to log in. It seems like the app can't even connect the RPi4. (error message in the app: "Connection to host: 192.168.x.yyy failed")