Hi there and welcome
Can you do the following please
First remove the soundlink from the bluetooth memory of your Mac. To do this, Choose Apple menu > System Preferences, then click Bluetooth. Hover the pointer over the device you want to remove, then click the button that appears next to the device's name
Then hold down the mute button on the Bose Soundlink for 10 seconds until all the lights start flashing. ..... Hold down the bluetooth button for 10 seconds until a beep is heard..... Then install the soundlink on the Mac again like you did when you first received it, then restart your Mac and Soundlink.
Tell me if its then working please.