USB Connectivty

my Arduino appear of line on my mobile app. while i follow the steps very carfully and i change the port to COM3 but i got this massage when i run blynk-ser.bat

Connecting device at COM3 to cloud.blynk.cc:8442…
OpenC0C("\.\COM3", baud=9600, data=8, parity=no, stop=1) - OK
Connect(“cloud.blynk.cc”, “8442”) - OK
InOut() START
DSR is OFF
Received EOF
EVENT_CLOSE

kindly advice

Anyone else have this problem? Didn’t experience it…