Manual:$wgHTCPPort

Details
UDP/IP port to which to multicast HTCP requests, originally used with $wgHTCPMulticastAddress. Both were deprecated in MediaWiki 1.20.0; use $wgHTCPMulticastRouting in MediaWiki 1.20.0 and $wgHTCPRouting for MediaWiki 1.22 and subsequent.

As of MediaWiki 1.23 the old variables are still supported (by being copied to their successors in includes/Setup.php) but are obsolete.