The transport option takes the name of the transport, if it’s not found then there is no transport by that name. You haven’t provided explicit configuration so I can’t say what it should be.
If 0.0.0.0 is used then it is up to the underlying operating system to route accordingly, and we ask the operating system what interface the packet will go out on and update the message accordingly.
How things should be configured and used very much depends on the specific network layout and what it is like.