ng server – listen EACCES: permission denied 127.0.0.1:4200

I have solved this issue by simply going to Control Panel\Network and Internet\Network Connections and then I disabled all the Hyper-V Connections/Adapters and I kept the ones I use like the Wifi and Physical Ethernet Adapter.

No restart needed.
Once done, try to run your Angular app on 4200 and it should work.

UPDATE

Alternative Solutions:

Sometimes just restarting Windows NAT driver can fix the issue:

• open CMD/PowerShell and type net stop winnat and then net start winnat.

If that did not help then, try to stop the Windows NAT Driver and update the excludedportrange as follows :

• type netsh int ipv4 add excludedportrange protocol=tcp startport=4200 numberofports=1 if you want to exclude port 4200 only if you want more just update numberofports
• then start the Windows NAT Driver again and run your App.