title: Timeout during allocate while making RFC call
body: <p>I am trying to create a SAP RFC connection to a new system.</p>
  
  <p>AFAIK the firewall (in this case to port 3321) is open.</p>
  
  <p>I get this message at the client:</p>
  
  <pre><code>RFC_COMMUNICATION_FAILURE (rc=1): key=RFC_COMMUNICATION_FAILURE, message=
  LOCATION    SAP-Gateway on host ax-swb-q06.prod.lokal / sapgw21
  ERROR       timeout during allocate
  TIME        Thu Jul 26 16:45:48 2018
  RELEASE     753
  COMPONENT   SAP-Gateway
  VERSION     2
  RC          242
  MODULE      /bas/753_REL/src/krn/si/gw/gwr3cpic.c
  LINE        2210
  DETAIL      no connect of TP sapdp21 from host 10.190.10.32 after 20 sec
  COUNTER     3
   [MSG: class=, type=, number=, v1-4:=;;;]
  </code></pre>
  
  <p>And this message on the SAP server</p>
  
  <p><a href="https://i.stack.imgur.com/cywLw.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/cywLw.png" alt="sap-syslog-screenshot"></a></p>
  
  <p>Any clue what needs to be done, to get RFC working?</p>