Plex doesn't show a network address for Alexa (at least not when playing music) but Tautulli does. Interestingly, Tautulli shows Alexa as coming from a WAN IP address (owned by Amazon Technologies Inc. according to whois) even though my Plex and Alexa devices are all on the same home LAN. Does that mean that Amazon is actually streaming the music from my Plex server and then re-streaming it to my Alexa device? Does anyone know, or is it time to install Wireshark on my Plex server and start digging in to its traffic?
FWIW, for all other devices in my home (Rokus, computer web browsers, cell phones on WiFi) Tautulli shows an address from my home network, so I think the IP address is a real thing ... unless Plex (or Tautulli) is intentionally changing it, which I seriously doubt.