In last resort, it will use your Peertube public URI.So, any API Call will go throught your Nginx server.This could fail in some case: for example if you are in a Docker container, where the public hostname does not resolve to the correct IP.In such case, try changing the "{{% livechat_label prosody_peertube_uri_label %}}" settings, by setting `http://127.0.0.1:9000` (assuming 9000 is the port on which Peertube listen, ask your instance administrators if you don't know).