If I insert headphones into the jack, everything works fine, the phone switches to headphones.
If I insert a wire to the amplifier (AUH) into the connector, the phone does not switch to this connector, it does not see anything at all and plays music on the built-in speaker. I downloaded an application that allows you to forcibly switch the playback direction, but I don't like this solution.
Earlier, when the phone was new, everything worked fine, when the AUX wire was connected, the phone switched to the jack and I listened to music on an external amplifier.