fix net error (#2460)

selector/node/ewma/node.go

@@ -4,6 +4,7 @@ import (
 	"container/list"
 	"context"
 	"math"
+	"net"
 	"sync"
 	"sync/atomic"
 	"time"
@@ -158,8 +159,9 @@ func (n *Node) Pick() selector.DoneFunc {
 			if n.errHandler != nil && n.errHandler(di.Err) {
 				success = 0
 			}
+			var netErr net.Error
 			if errors.Is(context.DeadlineExceeded, di.Err) || errors.Is(context.Canceled, di.Err) ||
-				errors.IsServiceUnavailable(di.Err) || errors.IsGatewayTimeout(di.Err) {
+				errors.IsServiceUnavailable(di.Err) || errors.IsGatewayTimeout(di.Err) || errors.As(di.Err, netErr) {
 				success = 0
 			}
 		}