unable to find my server



I have just installed a new Plex server on a windows 10 PC (Plex version and have configured remote access over port 32400. I can access the web page at https://app.plex.tv/web/app# and view all my media etc, but I cannot get the Alexa skill to find my server. Whenever I say "open plex", I get the "you're new around her ..." response followed by "I could not find any available servers. Please make sure your Plex media server is running and connected to the internet". Any thoughts on how I should go about debugging this