Restarting the smartphone can resolve a wide range of technical issues, including those related to Bluetooth connectivity. This simple step can refresh the system and eliminate temporary software glitches that might be interfering with Bluetooth functions like audio output and data synchronization.

Restart the smartphone: This action clears the system's RAM and can resolve conflicts between the Bluetooth service and other processes running on the smartphone, potentially fixing both the audio and synchronization issues.

Resetting network settings (B) could also potentially fix the issue but is a more drastic step that also clears Wi-Fi networks and passwords, cellular settings, and VPN configurations, which might not be necessary. Unpairing the Bluetooth speaker (C) could help if the issue is specific to the speaker, but since there are also synchronization issues with the smartwatch, the problem seems broader. Checking for system updates (D) is a good general maintenance step, but it's more likely to help with ongoing or known issues rather than immediate connectivity problems.