The Galaxy S21 has Bluetooth 5.0 and supports Samsung's Seamless codec for Galaxy Buds, and an S21 that now struggles with Bluetooth is often dealing with years of old pairings and a final software version. Open Settings, Connections, Bluetooth and remove devices you no longer use, then forget the one that fails and pair it again. For Galaxy Buds, Watch and similar, use the Galaxy Wearable app, which manages the connection and updates firmware. Dual audio lets two devices play at once and can leave a headset in an odd state, so switch it off in Bluetooth, Advanced.
The checks in more detail
Check Call audio and Media audio for the device. The S21's radio is shared with Wi-Fi; if audio stutters on 2.4 GHz, move to 5 GHz. A restart and a cache partition wipe after the last update help. If the phone loses the Bluetooth toggle, a network reset is the last step before service. Cars with old software may not pair with newer phones, so update the car. Some S21 owners noticed that Bluetooth worked better after turning off Bluetooth scanning under Location services,
which stops the phone scanning for nearby devices in the background, but that also reduces some Nearby features. Test with it off for a day. Keep the phone's software and the accessory's firmware current, because makers tune new releases for newer phones. If a Galaxy Watch is part of your set-up, remember that it pairs through the Galaxy Wearable app and also uses Bluetooth for notifications, so a watch that suddenly lags may have lost the link to the phone while the phone's own Bluetooth list looks normal.
Open the Wearable app, check that it shows Connected, and if not, toggle Bluetooth and reconnect there. After the S21's final software update, many owners needed to re-pair the watch once to restore full features. Samsung's Quick Share and Nearby share services also rely on Bluetooth and may hold the radio open while looking for devices, and turning Quick Share off for a day shows whether it is involved. If a car's hands-free system pairs but drops during calls, update the car's software or ask the dealer, because older cars have known bugs with newer phones.
Differential
Likely causes of “Samsung Galaxy S21 will not pair or stay connected over Bluetooth”, and how to tell them apart
- 1
Many old pairings
What separates it The device list is long and slow
How to confirm Remove devices you do not use
- 2
A stale pairing
What separates it The device will not connect
How to confirm Unpair and pair again
- 3
Dual audio enabled
What separates it A headset behaves oddly
How to confirm Turn off Dual audio
- 4
2.4 GHz interference
What separates it Audio stutters
How to confirm Use 5 GHz Wi-Fi
- 5
A car or accessory too old
What separates it Pairing fails
How to confirm Update the accessory's software
Before you touch a setting
Record this first — changing settings destroys the evidence
- The accessory and its age
- Whether Dual audio is on
- Whether stutter depends on Wi-Fi use
- The software version
Try in this order
0 of 8 completedRemove unused devices
ReversibleSettings, Connections, Bluetooth.
Unpair and pair again
ReversibleThe failing device.
Use Galaxy Wearable
ReversibleFor Samsung accessories.
Turn off Dual audio
ReversibleBluetooth, Advanced.
Use 5 GHz Wi-Fi
ReversibleTo reduce interference.
Wipe the cache partition
ReversibleFrom recovery mode.
Turn off Bluetooth scanning for a test
ReversibleSettings, Location, Location services, Improve accuracy.
Update the accessory firmware
ReversibleThrough its app.
Model-specific
What is true of this model and not of its siblings
- Pairing list
- A long list can slow connections.
- Galaxy Wearable
- It manages Samsung accessories.
- Background scanning
- It can disturb Bluetooth.
- Firmware
- Makers fix connection bugs.
Stop boundary
When this stops being a self-service repair
- !If the Bluetooth toggle will not switch on, contact Samsung
- !If one accessory fails, contact its maker
- !If a car refuses, ask the carmaker for an update
Evidence ledger
Sources behind this answer
Exact questions
Common questions
Why does my S21 Bluetooth drop?+
Interference or a stale pairing.
What is Dual audio?+
Two Bluetooth devices at once.
Which app handles Galaxy Buds?+
Galaxy Wearable.
Does the S21 support Bluetooth 5?+
Yes.
Can scanning affect Bluetooth?+
It can.
Should I update my headset?+
Yes.