Which controller ? The RC-N1 or the DJI-RC (with screen) ?
What version of Assitant2 ?
Windows Defender Firewall blocks:
C:\program files (x86)\dji product\dji assistant 2 (consumer drones series)\djiengine\djiservice.exe
and
C:\program files (x86)\dji product\dji assistant 2 (consumer drones series)\djiengine\djiservicecore.exe
You have to give Windows Defender Firewall permission to access them.
or
Any other installed and active firewall software.
Here's a screenshot (Windows 10 Home edition, Assistant 2 v2.1.10, DJI-RC):