If the connection breaks and timeouts occurs due to network problems and you cannot convince your network team, you can monitor events between client and listener for detailed review.
For this :
Add the following to the sqlnet.ora file on the client side.
TRACE_DIRECTORY_CLIENT=<where the trace files are written>
Add the following to the sqlnet.ora file on the server side.
TRACE_DIRECTORY_SERVER=<where the trace files are written>
When you restart listener, you will be able to see in detail what is happening in the listener trace.