Bridge MQTT broker on HA to other local MQTT server

I have the latest HA OS installed on a rpi4 where i am running the Mosquitto MQTT broker.
I want HA Mqtt broker to connect (bridge) to another broker running on my lan (Victron GX) .

Have added the file /etc/mosquitto.conf and /share/mosquitto/mosquitto.config Both i have added the following.
connection Victron
address 192.168.8.144:1883
topic N/c0847dc9a396/# in
topic R/c0847dc9a396/# out

The reason that i added it to /etc/mosquitto.conf is that the Mosquitto logs on my HA refers to it
See below
[15:52:09] INFO: Setup mosquitto configuration
[15:52:09] WARNING: SSL not enabled - No valid certs found!
[15:52:10] INFO: No local user available
[15:52:10] INFO: Initialize Hass.io Add-on services
[15:52:10] INFO: Initialize Home Assistant discovery
[15:52:10] INFO: Start Mosquitto daemon
1611586330: mosquitto version 1.6.3 starting
1611586330: Config loaded from /etc/mosquitto.conf.
1611586330: Loading plugin: /usr/share/mosquitto/auth-plug.so
1611586330: |-- *** auth-plug: startup
1611586330: ├── Username/password checking enabled.
1611586330: ├── TLS-PSK checking enabled.
1611586330: └── Extended authentication not enabled.
1611586330: Opening ipv4 listen socket on port 1883.
1611586330: Opening ipv6 listen socket on port 1883.
1611586330: Opening websockets listen socket on port 1884.
1611586330: Warning: Mosquitto should not be run as root/administrator.
1611586333: New connection from 172.30.32.1 on port 1883.
[INFO] found MQTTUser on Home Assistant
1611586334: New client connected from 172.30.32.1 as 4obtSPzwUveD5rpPGVJgKj (p2, c1, k60, u’MQTTUser’)

The problem is that it doesnt create a bridge to my other mqtt broker. It seems like it igonores the mosquitto.conf files

Have you change cuztomize option in the mosquitto addon configuration. It should look like this. With out this it wont read the config.

customize:
  active: true
  folder: mosquitto

May I ask why you need to bridge the two MQTT brokers instead of connecting HA to your existing one?

Yes, this is how my config looks like :

logins: []
anonymous: false
customize:
  active: true
  folder: mosquitto
certfile: fullchain.pem
keyfile: privkey.pem
require_certificate: false

Do you have any username or password with this broker?

No, its open. I can connect with MQTT explorer without username and password

My setup looks much the same as yours.

Did you restart the mosquitto add-on?

Probably should not be changing /etc/mosquitto.conf as I believe it is meant to be under the control of the add-on.
If you go inside the mosquitto container …
In the file /etc/mosquitto.conf
you should see it has uncommented the line ‘include_dir /share/mosquitto’
This is how it knows to go to that particular directory.

You can setup an MQTT bridge from either broker if that helps so there are two paths to do this.