Are you talking about the original Galaxy Watch which was released in 2018? If so, could that be your problem that it's nearing its end of life and not performing as expected any longer? If not, could provide the model number of the watch and some information on the steps you've tried pair it to your phone?
Greetings, depending on the watch especially if it's still running Tizen that support was lost on ONE UI 6 I believe. The only way it would connect is if it was already paired with the device before the update.
