Samsung Galaxy Tab A9+ will not pair or stay connected over Bluetooth

The checks in more detail

Remove the device from the tablet's list, restart both, and pair again, close to the tablet. A pairing that was made long ago can break after a software update, and removing it is the quickest cure. Because the tablet is large, it often sits on a desk beside a router and other wireless gear, and 2.4 GHz interference is the second commonest cause of stutter. Move a wireless mouse receiver or a USB hub away from the tablet, and check that the accessory is within a few meters without a wall between.

For audio, open the connected device's settings in Bluetooth and make sure Media audio is ticked, and in Settings, Sounds and vibration look at the sound output to confirm that the tablet is sending audio to the headset and not the speakers. If sound is delayed in video, try turning on the video latency option for the headset if shown, or try another headset, because delay is a property of the headset. Quad speakers on the tablet can sound as if the headset has failed when sound stays on the speakers.

On the battery side, Samsung's optimization can cut background connections when the screen is off, which makes a Bluetooth keyboard seem to fall asleep; check Settings, Battery, Background usage limits and take your accessories' companion apps out of any sleeping list. Update the tablet in Settings, Software update, and update the accessory's firmware in its app. If the tablet pairs with nothing, reset Bluetooth through Settings, General management, Reset, Reset Wi-Fi and Bluetooth settings. A device that fails on other tablets too is a faulty accessory. If nothing helps, contact Samsung with the model number from the back.