QN800B SmartThings app - unable to add device - "A network error has occurred"

I recently got a QN800B TV and in SmartThings I can’t click the + to add a device, as I get “A network error occurred. Please try again later.” The same happens when I try to access “Using SmartThings Hub” in the settings, and I’m unable to mirror my Z Fold 4 to the TV. Any suggestions?