diff --git a/kernel/model/sync.go b/kernel/model/sync.go
index fe7a9f677..97eb788b5 100644
--- a/kernel/model/sync.go
+++ b/kernel/model/sync.go
@@ -563,18 +563,21 @@ func planSyncAfter(d time.Duration) {
 
 func isProviderOnline() (ret bool) {
 	checkURL := util.SiYuanSyncServer
+	skipTlsVerify := false
 	switch Conf.Sync.Provider {
 	case conf.ProviderSiYuan:
 	case conf.ProviderS3:
 		checkURL = Conf.Sync.S3.Endpoint
+		skipTlsVerify = Conf.Sync.S3.SkipTlsVerify
 	case conf.ProviderWebDAV:
 		checkURL = Conf.Sync.WebDAV.Endpoint
+		skipTlsVerify = Conf.Sync.WebDAV.SkipTlsVerify
 	default:
 		logging.LogWarnf("unknown provider: %d", Conf.Sync.Provider)
 		return false
 	}
 
-	if ret = util.IsOnline(checkURL); !ret {
+	if ret = util.IsOnline(checkURL, skipTlsVerify); !ret {
 		util.PushErrMsg(Conf.Language(76), 5000)
 	}
 	return
diff --git a/kernel/util/net.go b/kernel/util/net.go
index b7a964a16..701380801 100644
--- a/kernel/util/net.go
+++ b/kernel/util/net.go
@@ -31,7 +31,7 @@ import (
 	"github.com/siyuan-note/logging"
 )
 
-func IsOnline(checkURL string) bool {
+func IsOnline(checkURL string, skipTlsVerify bool) bool {
 	_, err := url.Parse(checkURL)
 	if nil != err {
 		logging.LogWarnf("invalid check URL [%s]", checkURL)
@@ -42,7 +42,7 @@ func IsOnline(checkURL string) bool {
 		return false
 	}
 
-	if isOnline(checkURL) {
+	if isOnline(checkURL, skipTlsVerify) {
 		return true
 	}
 
@@ -50,10 +50,14 @@ func IsOnline(checkURL string) bool {
 	return false
 }
 
-func isOnline(checkURL string) (ret bool) {
+func isOnline(checkURL string, skipTlsVerify bool) (ret bool) {
+	c := req.C().SetTimeout(3 * time.Second)
+	if skipTlsVerify {
+		c.EnableInsecureSkipVerify()
+	}
+
 	for i := 0; i < 3; i++ {
-		c := req.C().SetTimeout(3 * time.Second)
-		_, err := c.R().Head(checkURL)
+		_, err := c.R().Get(checkURL)
 		ret = nil == err
 		if ret {
 			break