If the connection was lost between the Subwoofer and Soundbar, they can be paired together manually. In this video we show you how to get the subwoofer into pairing mode and what you’ll need to do on the Soundbar so that the pairing is successful!
You can read more about connecting your subwoofer and getting surround sound here: https://www.samsung.com/us/support/answer/ANS00049235/