diff --git a/kernel/api/sync.go b/kernel/api/sync.go
index 88f70b104..5facf7998 100644
--- a/kernel/api/sync.go
+++ b/kernel/api/sync.go
@@ -58,7 +58,7 @@ func performSync(c *gin.Context) {
 	}
 
 	if 3 != model.Conf.Sync.Mode {
-		model.SyncData(false, false, true)
+		model.SyncData(true)
 		return
 	}
 
diff --git a/kernel/model/conf.go b/kernel/model/conf.go
index 38dbc8bcd..7de936068 100644
--- a/kernel/model/conf.go
+++ b/kernel/model/conf.go
@@ -450,7 +450,7 @@ func Close(force bool, execInstallPkg int) (exitCode int) {
 	if !force {
 		if Conf.Sync.Enabled && 3 != Conf.Sync.Mode &&
 			((IsSubscriber() && conf.ProviderSiYuan == Conf.Sync.Provider) || conf.ProviderSiYuan != Conf.Sync.Provider) {
-			syncData(false, true, false)
+			syncData(true, false)
 			if 0 != ExitSyncSucc {
 				exitCode = 1
 				return
diff --git a/kernel/model/sync.go b/kernel/model/sync.go
index 3da736214..fe7a9f677 100644
--- a/kernel/model/sync.go
+++ b/kernel/model/sync.go
@@ -126,7 +126,7 @@ func SyncDataJob() {
 		return
 	}
 
-	SyncData(false, false, false)
+	SyncData(false)
 }
 
 func BootSyncData() {
@@ -170,19 +170,19 @@ func BootSyncData() {
 	return
 }
 
-func SyncData(boot, exit, byHand bool) {
-	syncData(boot, exit, byHand)
+func SyncData(byHand bool) {
+	syncData(false, byHand)
 }
 
-func syncData(boot, exit, byHand bool) {
+func syncData(exit, byHand bool) {
 	defer logging.Recover()
 
-	if !checkSync(boot, exit, byHand) {
+	if !checkSync(false, exit, byHand) {
 		return
 	}
 
 	util.BroadcastByType("main", "syncing", 0, Conf.Language(81), nil)
-	if !isProviderOnline() { // 这个操作比较耗时，所以要先推送 syncing 事件后再判断网络，这样才能给用户更即时的反馈
+	if !exit && !isProviderOnline() { // 这个操作比较耗时，所以要先推送 syncing 事件后再判断网络，这样才能给用户更即时的反馈
 		util.BroadcastByType("main", "syncing", 2, Conf.Language(28), nil)
 		return
 	}
@@ -190,11 +190,6 @@ func syncData(boot, exit, byHand bool) {
 	syncLock.Lock()
 	defer syncLock.Unlock()
 
-	if boot {
-		util.IncBootProgress(3, "Syncing data from the cloud...")
-		BootSyncSucc = 0
-		logging.LogInfof("sync before boot")
-	}
 	if exit {
 		ExitSyncSucc = 0
 		logging.LogInfof("sync before exit")
@@ -576,7 +571,7 @@ func isProviderOnline() (ret bool) {
 		checkURL = Conf.Sync.WebDAV.Endpoint
 	default:
 		logging.LogWarnf("unknown provider: %d", Conf.Sync.Provider)
-		util.IsOnline("")
+		return false
 	}
 
 	if ret = util.IsOnline(checkURL); !ret {
diff --git a/kernel/util/net.go b/kernel/util/net.go
index 7da8f1e38..b7a964a16 100644
--- a/kernel/util/net.go
+++ b/kernel/util/net.go
@@ -32,20 +32,13 @@ import (
 )
 
 func IsOnline(checkURL string) bool {
+	_, err := url.Parse(checkURL)
+	if nil != err {
+		logging.LogWarnf("invalid check URL [%s]", checkURL)
+		return false
+	}
+
 	if "" == checkURL {
-		if isOnline("https://www.baidu.com") {
-			return true
-		}
-
-		if isOnline("https://icanhazip.com") {
-			return true
-		}
-
-		if isOnline("https://api.ipify.org") {
-			return true
-		}
-
-		logging.LogWarnf("network is offline")
 		return false
 	}
 
@@ -57,10 +50,16 @@ func IsOnline(checkURL string) bool {
 	return false
 }
 
-func isOnline(checkURL string) bool {
-	c := req.C().SetTimeout(1 * time.Second)
-	_, err := c.R().Head(checkURL)
-	return nil == err
+func isOnline(checkURL string) (ret bool) {
+	for i := 0; i < 3; i++ {
+		c := req.C().SetTimeout(3 * time.Second)
+		_, err := c.R().Head(checkURL)
+		ret = nil == err
+		if ret {
+			break
+		}
+	}
+	return
 }
 
 func GetRemoteAddr(session *melody.Session) string {