diff --git a/pkg/mqtt/connection.go b/pkg/mqtt/connection.go
index 5ab2211..3944ce9 100644
--- a/pkg/mqtt/connection.go
+++ b/pkg/mqtt/connection.go
@@ -135,6 +135,7 @@ func (c *Connection) RcvMsgFromClient() {
 		}
 
 		server.Log.Infof("%s, come msg===\n%v\n=====", host, msg)
+		c.LastHbTime = time.Now().Unix()
 		switch msg := msg.(type) {
 		case *Connect:
 			ret := RetCodeAccepted
@@ -246,7 +247,6 @@ func (c *Connection) RcvMsgFromClient() {
 
 		case *PingReq:
 			server.Log.Infof("%s, ping req comes", host)
-			c.LastHbTime = time.Now().Unix()
 			pingrsp := &PingResp{}
 			err := c.Mgr.Provider.OnDeviceHeartBeat(c.DeviceId)
 			if err != nil {
diff --git a/pkg/mqtt/manager.go b/pkg/mqtt/manager.go
index c3d8777..73f54be 100644
--- a/pkg/mqtt/manager.go
+++ b/pkg/mqtt/manager.go
@@ -1,6 +1,7 @@
 package mqtt
 
 import (
+	"github.com/PandoCloud/pando-cloud/pkg/server"
 	"net"
 	"sync"
 	"time"
@@ -81,6 +82,7 @@ func (m *Manager) PublishMessage2Server(deviceid uint64, msg *Publish) error {
 
 func (m *Manager) CleanWorker() {
 	for {
+		server.Log.Infoln("scanning and removing inactive connections...")
 		curTime := time.Now().Unix()
 
 		for _, con := range m.IdToConn {
@@ -88,7 +90,8 @@ func (m *Manager) CleanWorker() {
 				continue
 			}
 
-			if uint16(curTime-con.LastHbTime) > uint16(2*con.KeepAlive/2) {
+			if uint16(curTime-con.LastHbTime) > uint16(3*con.KeepAlive/2) {
+				server.Log.Infof("connection %v inactive , removing", con)
 				con.Close()
 			}
 		}