diff --git a/internal/server/server.go b/internal/server/server.go
index d2a29f5..9262a6c 100644
--- a/internal/server/server.go
+++ b/internal/server/server.go
@@ -1184,11 +1184,24 @@ func (s *Server) defaultForwardRequestWithBodyFunc(w http.ResponseWriter, ctx co
 	return err
 }
 
-// proxyWebSocketCopy copies messages from src to dst
+// proxyWebSocketCopy copies messages from src to dst, forwarding close frames
+// to the destination so both peers receive a proper WebSocket close handshake.
 func proxyWebSocketCopy(src, dst *websocket.Conn) error {
 	for {
 		msgType, msg, err := src.ReadMessage()
 		if err != nil {
+			if closeErr, ok := err.(*websocket.CloseError); ok {
+				code := closeErr.Code
+				// RFC 6455: 1005, 1006, 1015 must not be sent on the wire.
+				switch code {
+				case websocket.CloseNoStatusReceived,
+					websocket.CloseAbnormalClosure,
+					websocket.CloseTLSHandshake:
+					code = websocket.CloseGoingAway
+				}
+				_ = dst.WriteMessage(websocket.CloseMessage,
+					websocket.FormatCloseMessage(code, closeErr.Text))
+			}
 			return err
 		}
 		if err := dst.WriteMessage(msgType, msg); err != nil {
@@ -1294,8 +1307,6 @@ func (s *Server) defaultProxyWebSocket(w http.ResponseWriter, r *http.Request, b
 		backendConn.Close()
 		return err
 	}
-	defer clientConn.Close()
-
 	// Proxy messages in both directions
 	errc := make(chan error, 2)
 	go func() {
@@ -1306,13 +1317,21 @@ func (s *Server) defaultProxyWebSocket(w http.ResponseWriter, r *http.Request, b
 		err := proxyWebSocketCopy(backendConn, clientConn)
 		errc <- err
 	}()
-	// Wait for one direction to fail/close
+	// Wait for one direction to fail/close, then immediately close both
+	// connections so the other goroutine unblocks and finishes cleanly.
 	err = <-errc
+	clientConn.Close()
+	backendConn.Close()
+	<-errc // wait for the second goroutine to finish
 
 	// Mark endpoint as unhealthy for WS if error is not a normal closure
 	if err != nil {
 		if isExpectedWSClose(err) {
-			log.Debug().Err(err).Str("endpoint", helpers.RedactAPIKey(backendURL)).Msg("WebSocket connection closed normally")
+			if closeErr, ok := err.(*websocket.CloseError); ok && closeErr.Code == websocket.CloseAbnormalClosure {
+				log.Debug().Err(err).Str("endpoint", helpers.RedactAPIKey(backendURL)).Msg("WebSocket connection closed abnormally (1006), not counting as failure")
+			} else {
+				log.Debug().Err(err).Str("endpoint", helpers.RedactAPIKey(backendURL)).Msg("WebSocket connection closed normally")
+			}
 			return nil
 		}
 		if chain, endpointID, found := s.findChainAndEndpointByURL(backendURL); found {