Added MMM-MQTT.

            {
                address: 'random_numbers-ats.iot.eu-west-2.amazonaws.com',          // Server address or IP address
                port: '8883',                  // Port number if other than default
                ca: 'random_numbers-random_numbers-random_numbers-certificate.pem.crt.txt', // Path to trusted CA certificate file (optional)
                // clientId: 'mirror',         // Custom MQTT client ID (optional)
                //user: 'user',                  // Leave out for no user
                //password: 'password',          // Leave out for no password
                subscriptions: [
                    {
                        topic: 'nr_test_1', // Topic to look for
                        label: 'Timestamp', // Displayed in front of value

Address - tried IP of other 'Pi. (.35) Tried Amazon IoT address
Port - Tried 1883 and 8883
Does MMM-MQTT not need the private key as well as the ca cert?
(I’m not using user and password.)

MM shows only MQTT and Timestamp, but no live data.

What have I missed on the setup for this, please?