Transferred Calls in Teams Luware or Queues with no Audio on recipients side and broken connection

Dear All,

we are facing problems with forwarded calls in Teams. We use the Teams addon Luware/Nimbus to transfer calls from one location to another location via a transfer workflow. When the call is transferred, the recipient cannot hear the caller, but the caller can hear the recipient. This happens not in all cases, so sometimes the calls are working fine. We also opened different firewall ports and sometimes it is working but after a while the same issue happens again. We also tried to directly transfer the calls to a Teams Queue. It worked for a few tests, but then we went into the same issue. Only calls are working which are directly routed to a single user.

Can anyone help us?

Best Regards

Robert