K3/0-mini and Remoterig sold by Elecraft recommend using ports 13000, 13001, and 13002. Recently, upon switching over to Tampa area Internet provider FIOS, I discovered remote RRC no longer had audio and would shut itself off after a few seconds. Traced problem to the fact that Verizon is apparently blocking the recommended audio port, 13001. Easy solution was to use port 13003 for audio.