Well I found 1 issue, the MQ-container didn't have this in the config:

listener 8883

So it did not listen on that port🤦‍♂️. I now can actually connect to it with telnet and nmap shows the port is now open. Now i can see the following error in my MQ logs:

1651665669: New connection from 87.253.149.198:55066 on port 8883.
 1651665669: Client <unknown> disconnected due to malformed packet.
 1651665669: New connection from 87.253.149.213:50366 on port 8883.
 1651665669: Client <unknown> disconnected due to malformed packet.
 1651665670: New connection from 87.253.149.198:55068 on port 8883.
 1651665670: Client <unknown> disconnected due to malformed packet.
 1651665672: New connection from 87.253.149.213:50368 on port 8883.
 1651665672: Client <unknown> disconnected due to malformed packet.
 1651665672: New connection from 172.20.0.2:57990 on port 1883.
 1651665672: Client ydRrLDYofXi6kVhDb4XkbGi disconnected, not authorised.
 1651665672: New connection from 172.20.0.2:57992 on port 1883.
 1651665672: Client ydRrLDYofXi6kVhDb4XkbGi disconnected, not authorised.
 1651665673: New connection from 87.253.149.198:55070 on port 8883.
 1651665673: Client <unknown> disconnected due to malformed packet.
 1651665673: New connection from 87.253.149.213:50370 on port 8883.
 1651665673: Client <unknown> disconnected due to malformed packet.