com.aws.greengrass.mqttclient.AwsIotMqttClient: Unable to connect to AWS IoT Core

Thank you so much Michael. One more question if you do not mind. Is there anyway to change it locally without connecting to online?

In the same way you set the dataplane port, you may create a configuration file which contains the necessary configuration underneath the aws.greengrass.Nucleus key.

services:
  aws.greengrass.Nucleus:
    configuration:
      mqtt:
        port: 443

You can also have a look at our manual installation instructions which have a bit more information about creating a local config file and using that. https://docs.aws.amazon.com/greengrass/v2/developerguide/manual-installation.html#:~:text=in%20an%20HSM.-,Install%20the%20AWS%20IoT%20Greengrass%20Core%20software%20with%20private%20key%20and%20certificate%20files,-Install%20the%20AWS

It is working now after i changed both mqtt and greengrassDataPlanePort to 443. Thank you so much Michael.