Home Assistant / MQTT

Hey there,

running HA with umbrel.
Having trouble with MQTT.

MQTT Broker runs on separate machine.
IOT Devices are able to connect to broker.
MQTT Explorer proves that messages are transmitted.

HA can connect to broker as well.
When sending MQTT Messages within HA then HA can also see it’s own messages when listening to the accruing topic.

HA can’t see other topics at all.
Can this be a firewall/port forwarding issue by umbrel?
Appreciate any ideas/hints/solutions.