Port forwards to my web / mail server are failing

Article #: Product Castle
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Port forward to my web / mail server fails to work — what can I check?


A port forward rule has been created to route mail traffic to the web / mail server, but external machines are unable to connect


Check that the default gateway setting on the web / mail server is using the internal Smoothwall IP address.

It is recommended you power cycle the router in front of the Smoothwall to clear the ARP cache (Address Resolution Protocol) on the device, if:

  • the web / mail server was previously on a public IP address and has now been moved to a new IP address behind a Smoothwall
  • the original public IP address was been configured on the Smoothwall as the primary connection IP address or as an alias

That should allow the router to refresh its ARP entries to point to the Smoothwall instead of the original network card.


Last updated: Author: Contributions by:
30 August 2016   Tanja