Nginx Error (104: Connection reset by peer)

I have some errors all the time on NGINX server :

[error] 867#867: *4397 recv() failed (104: Connection reset by peer) while proxying upgraded connection, client: <computer_IP>, server: <jitsi_domain>, request: “GET /xmpp-websocket?room=<room_name> HTTP/1.1”, upstream: “http://<prosody_IP>:5280/xmpp-websocket?prefix=&room=test123”, host: “<jitsi_domain>”