Once a Jetson is flashed, it will automatically reboot. It is at this stage that optional software is added, and the addition uses ssh. If the USB sets up correctly, then there is a virtual network device the host PC will see on that USB cable which acts like a network router. The host PC will get an additional interface if security does not block it, and the address of the Jetson will be 192.168.55.1. This is the address you would use for that case (incidentally, ifconfig on the host PC would show an interface with address 192.168.55.100, and the host could ping itself with “ping 192.168.55.100”, or could ping the Jetson with “ping 192.168.55.1”; either of those is a good test to know if the virtual network is up.
If you happen to have a wired ethernet connection, and the Jetson is connected, then it just takes the DHCP address your router assigns. The host PC could use the Jetson’s ethernet address from that if desired, but you’d have to go to the Jetson and look at ifconfig to find out the address your router assigned. Wired ethernet does tend to be faster.