Thank you for your reply.
I checked “connection preferences” and I don't see anything that could help (I'm talking about the connection with the “Datacolor reder” that I have on hand).
I noticed that when certain Bluetooth devices are detected and I click “pair,” nothing happens. Whereas, for example, with OPPO Enco Free2 headphones, there's no problem; they are detected.
I haven't installed “Google Play,” only “Play Store”... Could that be the problem? If so, how can I install it in “sandbox” mode (just to be sure I'm doing it right)?