Weinzierl 731 IP Interface looses connection

Hello my name is Christian and i just joined this forum.

Unfortunately I can’t get a stable connection to my bus.

If I establish a connection from my ETS 5 to the bus, the Gateway from openhab works well, as long as the connection from ETS stays online.

If I close ETS the connection from openhab gets broken too within a few seconds to a few minutes with following error: timeout connecting to control endpoint

My Setup:

Openhab 3.2.0 on Ubuntu (also tried it with openhabian on raspi, same issue… )
KNX interface Weinzierl 731

UID: knx:ip:03c41axxxx
label: KNX/IP Gateway
thingTypeUID: knx:ip
useNAT: false
readRetriesLimit: 3
autoReconnectPeriod: 60
type: TUNNEL
localSourceAddr: 0.0.0
readingPause: 50
portNumber: 3671
responseTimeout: 10

I have tried various settings but nothing worked.

So I hope you can help me

Yours sincerely