@haloway13
@ncollins
Woot!!! massive success!!!

in /srv/openhab-userdata/config/org/openhab/mqttbroker.config

added at the end secure="false"

as you suggested.

21:42:04.192 [INFO ] [openhab.event.ItemStateChangedEvent  ] - Item 'HumiditySensor_Humidity' changed from 33.1 to 33.3
21:42:54.224 [DEBUG] [protocol.mqtt.MySensorsMqttConnection] - MQTT message received. Topic: mygateway1-out/1/1/1/0/1, Message: 33.2
21:42:54.226 [DEBUG] [protocol.mqtt.MySensorsMqttConnection] - Message topic part: 1/1/1/0/1
21:42:54.228 [DEBUG] [protocol.mqtt.MySensorsMqttConnection] - Converted MQTT message to MySensors Serial format. Sending on to bridge: 1;1;1;0;1;33.2
21:42:54.231 [DEBUG] [orsAbstractConnection$MySensorsReader] - Message from gateway received: 1;1;1;0;1;33.2
21:42:54.234 [DEBUG] [ors.internal.gateway.MySensorsGateway] - Node 1 found in gateway
21:42:54.236 [DEBUG] [ors.internal.gateway.MySensorsGateway] - Child 1 found in node 1
21:42:54.238 [DEBUG] [sensors.handler.MySensorsThingHandler] - Updating channel: hum(V_HUM) value to: 33.2
21:42:54.244 [INFO ] [openhab.event.ItemStateChangedEvent  ] - Item 'HumiditySensor_Humidity' changed from 33.3 to 33.2
21:42:54.246 [DEBUG] [sensors.handler.MySensorsThingHandler] - Setting last update for node/child 1/1 to 2021-03-11T21:42:54.000-0700
21:43:04.250 [DEBUG] [protocol.mqtt.MySensorsMqttConnection] - MQTT message received. Topic: mygateway1-out/1/1/1/0/1, Message: 33.3
21:43:04.252 [DEBUG] [protocol.mqtt.MySensorsMqttConnection] - Message topic part: 1/1/1/0/1
21:43:04.253 [DEBUG] [protocol.mqtt.MySensorsMqttConnection] - Converted MQTT message to MySensors Serial format. Sending on to bridge: 1;1;1;0;1;33.3
21:43:04.260 [DEBUG] [orsAbstractConnection$MySensorsReader] - Message from gateway received: 1;1;1;0;1;33.3
21:43:04.262 [DEBUG] [ors.internal.gateway.MySensorsGateway] - Node 1 found in gateway
21:43:04.263 [DEBUG] [ors.internal.gateway.MySensorsGateway] - Child 1 found in node 1
21:43:04.265 [DEBUG] [sensors.handler.MySensorsThingHandler] - Updating channel: hum(V_HUM) value to: 33.3
21:43:04.270 [INFO ] [openhab.event.ItemStateChangedEvent  ] - Item 'HumiditySensor_Humidity' changed from 33.2 to 33.3
21:43:04.271 [DEBUG] [sensors.handler.MySensorsThingHandler] - Setting last update for node/child 1/1 to 2021-03-11T21:43:04.000-0700
21:43:14.266 [DEBUG] [protocol.mqtt.MySensorsMqttConnection] - MQTT message received. Topic: mygateway1-out/1/1/1/0/1, Message: 33.2
21:43:14.268 [DEBUG] [protocol.mqtt.MySensorsMqttConnection] - Message topic part: 1/1/1/0/1
21:43:14.271 [DEBUG] [protocol.mqtt.MySensorsMqttConnection] - Converted MQTT message to MySensors Serial format. Sending on to bridge: 1;1;1;0;1;33.2
21:43:14.276 [DEBUG] [orsAbstractConnection$MySensorsReader] - Message from gateway received: 1;1;1;0;1;33.2
21:43:14.278 [DEBUG] [ors.internal.gateway.MySensorsGateway] - Node 1 found in gateway
21:43:14.280 [DEBUG] [ors.internal.gateway.MySensorsGateway] - Child 1 found in node 1
21:43:14.281 [DEBUG] [sensors.handler.MySensorsThingHandler] - Updating channel: hum(V_HUM) value to: 33.2
21:43:14.285 [INFO ] [openhab.event.ItemStateChangedEvent  ] - Item 'HumiditySensor_Humidity' changed from 33.3 to 33.2
21:43:14.286 [DEBUG] [sensors.handler.MySensorsThingHandler] - Setting last update for node/child 1/1 to 2021-03-11T21:43:14.000-0700

so to follow up:

Here is the log after adding the thing systembroker:

21:28:27.906 [INFO ] [o.transport.mqtt.MqttBrokerConnection] - Starting MQTT broker connection to '192.168.1.151' with clientid bd9a756d-5cf7-46b0-adaa-856d29f8b587
21:29:27.913 [INFO ] [t.reconnect.PeriodicReconnectStrategy] - Try to restore connection to '192.168.1.151'. Next attempt in 60000ms
21:29:27.920 [INFO ] [o.transport.mqtt.MqttBrokerConnection] - Starting MQTT broker connection to '192.168.1.151' with clientid bd9a756d-5cf7-46b0-adaa-856d29f8b587
21:30:27.925 [INFO ] [t.reconnect.PeriodicReconnectStrategy] - Try to restore connection to '192.168.1.151'. Next attempt in 60000ms
21:30:27.933 [INFO ] [o.transport.mqtt.MqttBrokerConnection] - Starting MQTT broker connection to '192.168.1.151' with clientid bd9a756d-5cf7-46b0-adaa-856d29f8b587
21:31:05.860 [INFO ] [openhab.event.InboxRemovedEvent      ] - Discovery Result with UID 'mqtt:systemBroker:mosquitto' has been removed.
21:31:06.015 [INFO ] [hab.event.ThingStatusInfoChangedEvent] - Thing 'mqtt:systemBroker:mosquitto' changed from UNINITIALIZED to INITIALIZING
21:31:06.072 [INFO ] [hab.event.ThingStatusInfoChangedEvent] - Thing 'mqtt:systemBroker:mosquitto' changed from INITIALIZING to OFFLINE
21:31:06.079 [INFO ] [o.transport.mqtt.MqttBrokerConnection] - Starting MQTT broker connection to '192.168.1.151' with clientid bd9a756d-5cf7-46b0-adaa-856d29f8b587
21:31:06.130 [INFO ] [hab.event.ThingStatusInfoChangedEvent] - Thing 'mqtt:systemBroker:mosquitto' changed from OFFLINE to OFFLINE (COMMUNICATION_ERROR): Timeout
21:31:06.135 [INFO ] [hab.event.ThingStatusInfoChangedEvent] - Thing 'mqtt:systemBroker:mosquitto' changed from OFFLINE (COMMUNICATION_ERROR): Timeout to OFFLINE (COMMUNICATION_ERROR): java.io.IOException: Connection reset by peer
21:31:27.938 [INFO ] [t.reconnect.PeriodicReconnectStrategy] - Try to restore connection to '192.168.1.151'. Next attempt in 60000ms
21:31:27.943 [INFO ] [hab.event.ThingStatusInfoChangedEvent] - Thing 'mqtt:systemBroker:mosquitto' changed from OFFLINE (COMMUNICATION_ERROR): java.io.IOException: Connection reset by peer to OFFLINE
21:31:27.951 [INFO ] [o.transport.mqtt.MqttBrokerConnection] - Starting MQTT broker connection to '192.168.1.151' with clientid bd9a756d-5cf7-46b0-adaa-856d29f8b587
21:31:27.986 [INFO ] [hab.event.ThingStatusInfoChangedEvent] - Thing 'mqtt:systemBroker:mosquitto' changed from OFFLINE to OFFLINE (COMMUNICATION_ERROR): java.io.IOException: Connection reset by peer
21:32:27.956 [INFO ] [t.reconnect.PeriodicReconnectStrategy] - Try to restore connection to '192.168.1.151'. Next attempt in 60000ms
21:32:27.967 [INFO ] [o.transport.mqtt.MqttBrokerConnection] - Starting MQTT broker connection to '192.168.1.151' with clientid bd9a756d-5cf7-46b0-adaa-856d29f8b587
21:32:27.968 [INFO ] [hab.event.ThingStatusInfoChangedEvent] - Thing 'mqtt:systemBroker:mosquitto' changed from OFFLINE (COMMUNICATION_ERROR): java.io.IOException: Connection reset by peer to OFFLINE
21:32:28.014 [INFO ] [hab.event.ThingStatusInfoChangedEvent] - Thing 'mqtt:systemBroker:mosquitto' changed from OFFLINE to OFFLINE (COMMUNICATION_ERROR): java.io.IOException: Connection reset by peer

Here is how I configured the thing: