I have configured an MQTT bridge to AWS IoT from Mosquitto on Home Assistant. Mosquitto installed via add-on (standard from Supervisor | Add-ons) and bridge file created as per instructions.
Running this I get the following messages in the Mosquitto log file
2020-10-23T06:29:56.855055000Z 1603434596: New client connected from 192.168.1.240 as MqttDashboard-8679153 (p2, c1, k30, u'mqttuser').
2020-10-23T06:29:56.857363000Z 1603434596: No will message specified.
2020-10-23T06:29:56.857605000Z 1603434596: Sending CONNACK to MqttDashboard-8679153 (0, 0)
2020-10-23T06:29:57.158545000Z 1603434597: Bridge local.bridgeawsiot doing local SUBSCRIBE on topic homeassistant/sun/sun/azimuth
2020-10-23T06:29:57.158937000Z 1603434597: Connecting bridge awsiot (a1mpax8uhmvady-ats.iot.us-east-1.amazonaws.com:8883)
2020-10-23T06:29:57.167846000Z 1603434597: Bridge bridgeawsiot sending CONNECT
2020-10-23T06:29:58.131523000Z 1603434598: Received CONNACK on connection local.bridgeawsiot.
2020-10-23T06:29:58.132811000Z 1603434598: Bridge local.bridgeawsiot sending UNSUBSCRIBE (Mid: 2, Topic: homeassistant/sun/sun/azimuth)
2020-10-23T06:29:58.133049000Z 1603434598: Sending PUBLISH to local.bridgeawsiot (d0, q0, r1, m0, 'homeassistant/sun/sun/azimuth', ... (6 bytes))
2020-10-23T06:29:58.386787000Z 1603434598: Received UNSUBACK from local.bridgeawsiot
2020-10-23T06:29:58.587056000Z 1603434598: Socket error on client local.bridgeawsiot, disconnecting.
2020-10-23T06:30:04.295149000Z 1603434604: Bridge local.bridgeawsiot doing local SUBSCRIBE on topic homeassistant/sun/sun/azimuth
2020-10-23T06:30:04.296839000Z 1603434604: Connecting bridge awsiot (xxxxxxxxxxxxxx-ats.iot.us-east-1.amazonaws.com:8883)
2020-10-23T06:30:04.306487000Z 1603434604: Bridge bridgeawsiot sending CONNECT
2020-10-23T06:30:05.280315000Z 1603434605: Received CONNACK on connection local.bridgeawsiot.
2020-10-23T06:30:05.280853000Z 1603434605: Bridge local.bridgeawsiot sending UNSUBSCRIBE (Mid: 3, Topic: homeassistant/sun/sun/azimuth)
2020-10-23T06:30:05.281324000Z 1603434605: Sending PUBLISH to local.bridgeawsiot (d0, q0, r1, m0, 'homeassistant/sun/sun/azimuth', ... (6 bytes))
2020-10-23T06:30:05.533389000Z 1603434605: Received UNSUBACK from local.bridgeawsiot
2020-10-23T06:30:05.733945000Z 1603434605: Socket error on client local.bridgeawsiot, disconnecting.
Any idea why this keeps disconneting?