Android adb command for host, provides a command line option if you want to connect to one specific device using serial number, when you have more than 1 mobile/device is connected over USB or if abd is connected over network.
The option for adb is ” -s
Check the serial number of the device you want to connect to,
$ adb devices List of devices attached B2NGAA8831702707 device1 A4NTXY6734562309 device2
Now, lets say if we want to connect to device1, then use below command,
$ adb -s B2NGAA8831702707 shell
Above command should connect to first device.