diff --git a/QtScrcpy/server/server.cpp b/QtScrcpy/server/server.cpp
index 4fc2ec8..3112a0d 100644
--- a/QtScrcpy/server/server.cpp
+++ b/QtScrcpy/server/server.cpp
@@ -155,11 +155,7 @@ bool Server::execute()
 }
 
 bool Server::start(const QString& serial, quint16 localPort, quint16 maxSize, quint32 bitRate, const QString& crop)
-{
-    if (serial.isEmpty()) {
-        return false;
-    }
-
+{    
     m_serial = serial;
     m_localPort = localPort;
     m_maxSize = maxSize;
diff --git a/QtScrcpy/videoform.cpp b/QtScrcpy/videoform.cpp
index f3113e8..30d250a 100644
--- a/QtScrcpy/videoform.cpp
+++ b/QtScrcpy/videoform.cpp
@@ -79,7 +79,9 @@ VideoForm::VideoForm(QWidget *parent) :
     // support 480p 720p 1080p
     //m_server->start("P7C0218510000537", 27183, 0, 8000000, "");
     //m_server->start("P7C0218510000537", 27183, 1080, 8000000, "");
-    m_server->start("P7C0218510000537", 27183, 720, 8000000, "");
+
+    // only one devices, serial can be null
+    m_server->start("", 27183, 720, 8000000, "");
 
     // support wireless connect
     //m_server->start("192.168.0.174:5555", 27183, 720, 8000000, "");