I’ve found this as a result of the new limitations within IFTTT. I’ve been trying to install it using the new SmartThings app, but am receiving the Error 403 when I try to do the Google authentication. I’ve checked all my settings within the web client OAuth and they are correct. The only thing that I can think of is that the new app forces authentication to take place inside the app rather than a browser. Reading through this thread, I see that this was corrected back in 2017 using ‘external’ but this doesn’t seem to work with the new app. Any ideas?