I've just applied the settings above and retried ITVx using Surfshark. I selected Marcella episode 1 and it plays for 90 seconds and then there is a slight pause. This repeats a couple of times and then I get the "Something went wrong" message.
It's not Korat, but a friend of mine recently renewed his DLs at Nang Rong (Buriram) and they did accept a letter from Nang Rong police station as a replacement for a CoR issued by immigration.
@Digitalbanana have you added your gender to the "Gender" field in the address record and saved it? That could be what the "red message" is asking you to do, and why your address doesn't appear in screen 2.