Jetson AGX xavier

i bought new AGX kit, i installed jetpack in my linux ubantu 18.04, while flashing i got one error i.e. connect to host 192.168.55.1 port 22: connection time out
rsync: connection unexpectedly closed (0 bytes received so far) [sender]
rsync error: unexplained error (code 255) at io.c(235) [sender=3.1.2]
please help me out with this.