HassIO and mosquitto

Configuration
1

Hi,
I’m trying to configure the integrated mosquitto broker in hassio but I have some troubles.
This is my mosquitto configuration:

  "plain": true,
  "ssl": true,
  "anonymous": false,
  "logins": [
    {
      "username": "user",
      "password": "password"
    }
  ],
  "customize": {
    "active": false,
    "folder": "mosquitto"
  },
  "certfile": "certificate.pem",
  "keyfile": "privkey.pem"
}

My configuration.yaml

mqtt:
    broker: 172.17.0.1
    client_id: hassio-1
    username: user
    password: password
    port: 8883
    certificate: /ssl/certificate.crt

With these configurations I got the error:
ssl.SSLError: [SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed (_ssl.c:749)

If I use the port 1883, without certificate, everythings works, I have tested mosquitto broker from my pc with that certificate.crt and works.
What could be the problem?

Thanks