Improved url online checking logic

Improved url online checking logic. When 401 is returned, it can also be recognized as online

kernel/util/net.go

@@ -100,6 +100,11 @@ func isOnline(checkURL string, skipTlsVerify bool) (ret bool) {
 
 	for i := 0; i < 3; i++ {
 		resp, err := c.R().Get(checkURL)
+
+		if resp.StatusCode == 401 {
+			return true
+		}
+
 		if resp.GetHeader("Location") != "" {
 			return true
 		}