Statuscode 503 (Service Unavailable) when decrypting CoreML model

Yesterday evening, upon a fresh install, my app was not able to decrypt the CoreML model and kept returning status code 503. I understood this as: Apple's service to download the decryption key is not available at the moment. This problem persisted for at least 8 hours. Three questions:

1. Does that occur more often? It means that during such times, new customers of my app will not be able to use the app.
2. Anyone has some sample code on how to identify this situation / extract the status code from the error object? (Instead of error 'You need an internet connection' I would like to issue error 'Apple server currently not available - try again later')
3. Anyone knows how to force/simulate this situation so that I can analyse the error object and see how I can identify the situation?

Below my code to retrieve the model:

NSURL *modelUrl = [[NSBundle mainBundle] URLForResource:modelName withExtension:@"mlmodelc"];

[MLModel loadContentsOfURL:modelUrl
                 configuration:[[MLModelConfiguration alloc] init]
             completionHandler:^(MLModel *loadedModel, NSError *error) {
        if (nil == loadedModel) {
            NSLog(@"Error loading model: %@", (nil != error) ? error : modelUrl);