If you are getting the “Thread network credentials does not match with any of the active thread networks around”, then probably what has happened is that your iPhone already has Thread Credentials but they are old. You’ll need to go to Companion App UI->Settings->Companion App->Debugging->Thread and see if you have any entries under “Apple Keychain”. If you do, then touch the entry(ies) and slide it to the left to reveal a trash can and then delete it. Now try the method to send the credentials to the phone and see what happens.