Usually that’s caused by the WinNAT service, restarting which solves the issue.
Just open the Command Prompt or PowerShell as Administrator, and type the following commands there:
net stop winnat net start winnat
And wait a bit for the Android Studio to reconnect to the ADB.
P.S. If it doesn’t reconnect, just type the following commands to restart the ADB:
adb kill-server adb start-server