MQTTブリッジに接続するためのプロキシを設定するにはどうすればよいですか？

会社のプロキシの背後にあるLinuxでmosquittoブローカーを実行しています。AWSへのブリッジを次のように構成しました：（mosquitto.conf）

connection bridge
address ec2-xxx-xxx-xxx-xxx.ap-northeast-1.compute.amazonaws.com:8089
remote_username admin
remote_password password
topic abc/raspi01 both 0
bridge_cafile /etc/pki/tls/certs/nginx-selfsigned.crt
bridge_insecure false

しかし、コマンドでmosquittoサービスを開始すると：

service mosquitto restart

ログファイルに、いくつかのエラーがあります。

1554356888: mosquitto version 1.5.5 starting
1554356888: Config loaded from /etc/mosquitto/mosquitto.conf.
1554356888: Opening ipv4 listen socket on port 1883.
1554356888: Opening ipv6 listen socket on port 1883.
1554356888: Warning: Address family not supported by protocol
1554356888: Connecting bridge bridge (ec2-xxx-xxx-xxx-xxx.ap-northeast-1.compute.amazonaws.com:8089)
1554356888: Error creating bridge: Name or service not known.
1554356888: Warning: Unable to connect to bridge bridge.
1554356901: New connection from 127.0.0.1 on port 1883.
1554356901: New connection from 127.0.0.1 on port 1883.
1554356901: New client connected from 127.0.0.1 as mqtt_fd05fada.b70918 (c1, k60).
1554356901: New client connected from 127.0.0.1 as mqtt_2a3a025d.6c941e (c1, k60).
1554356919: Connecting bridge bridge (ec2-xxx-xxx-xxx-xxx.ap-northeast-1.compute.amazonaws.com:8089)
1554356919: Error creating bridge: Name or service not known.
1554356950: Connecting bridge bridge (ec2-xxx-xxx-xxx-xxx.ap-northeast-1.compute.amazonaws.com:8089)
1554356950: Error creating bridge: Name or service not known.

原因は会社の代理人だと思います。mosquitto.serviceの設定を試してみましたが、解決しません。

[Unit]
Description=Mosquitto MQTT v3.1/v3.1.1 Broker
Documentation=man:mosquitto.conf(5) man:mosquitto(8)
After=network-online.target
Wants=network-online.target

[Service]
Type=notify
NotifyAccess=main
ExecStart=/usr/sbin/mosquitto -c /etc/mosquitto/mosquitto.conf
Environment="HTTPS_PROXY=http://user:pass@proxyhost:8800"
Environment="HTTP_PROXY=http://user:pass@proxyhost:8800"
Environment="NO_PROXY=127.0.0.1,localhost"
Restart=on-failure

[Install]
WantedBy=multi-user.target

誰かが私を助けることができますか？ありがとうございます。