This action attempts to begin hosting the Lacewing Relay protocol part of the server.
It takes one parameter, which is the port to host on; a number from 1 to 65535, inclusive. The default port for Lacewing Relay protocol is 6121.
This may trigger an error, for instance, when there is already a server on the machine (of any kind) hosting on the specified port, be it TCP, UDP, or both.
See more details on the Hosting a server page.