WebSocket connection drops behind reverse proxy or load balancer

WebSocket connections work locally but drop after 60 seconds in production. Behind nginx or a cloud load balancer, the WebSocket upgrade succeeds but the connection is closed after a timeout period.

(1) Nginx: set proxy_read_timeout to a higher value (default 60s closes idle WebSocket connections). Add: proxy_read_timeout 3600s. (2) Add WebSocket headers: proxy_http_version 1.1; proxy_set_header Upgrade $http_upgrade; proxy_set_header Connection 'upgrade'. (3) AWS ALB: idle timeout defaults to 60s — increase in target group settings. (4) CloudFlare: WebSocket support must be enabled, 100s idle timeout on free plan. (5) Implement ping/pong heartbeats: send a ping every 30s to keep the connection alive. (6) Client-side: implement automatic reconnection with exponential backoff.

Reverse proxies and load balancers close idle connections to free resources. WebSocket connections are long-lived and appear idle to the proxy when no data is being sent.