Remote Desktop (RDP) failures are usually one of: target not reachable, credentials wrong, target service not running, or VPN required.

1. Can you reach the target at all?

Open Command Prompt and ping the target:

ping <hostname or IP>
  • If ping fails, you can't reach the network — VPN may be required, or the target is off
  • If ping succeeds, RDP itself is the issue

2. Is RDP enabled on the target?

RDP is disabled by default on most Windows installations. On the target machine:

  1. Settings → System → Remote Desktop
  2. Toggle Enable Remote Desktop on
  3. Note the PC name shown — that's what you connect to

If you can't reach the target physically, get a sysadmin to do this for you.

3. Is the RDP port open?

RDP uses TCP port 3389 by default. Test:

Test-NetConnection -ComputerName <target> -Port 3389

(PowerShell, Windows)

If TcpTestSucceeded is False, a firewall is blocking it.

4. Credentials format

RDP can be picky about how you enter your username:

  • username alone — may default to the wrong domain
  • domain\username — explicit
  • [email protected] — also explicit

Try both forms if one fails.

5. Wrong password counter

Active Directory locks accounts after a number of failed attempts. If you've been trying with a wrong password, the account may be locked even when you have the right one. Wait the lockout interval (often 15 min) or contact IT to unlock.

6. Restart the RDP service on target

If you have console access to the target:

  1. services.msc
  2. Find Remote Desktop Services
  3. Restart it

Or PowerShell: Restart-Service TermService

7. Network Level Authentication (NLA)

Some configurations require NLA before allowing the connection. Modern RDP clients handle this automatically; older ones may show "this computer can't connect to the remote computer" without further detail.

Update your RDP client: in Windows, search for Remote Desktop Connection; it auto-updates with Windows.

8. VPN required

Most corporate networks require VPN before RDP works. If you're outside the office network:

  1. Connect to VPN first
  2. Then attempt RDP

If RDP works on VPN but not direct, that's expected — RDP is rarely exposed to the internet for security reasons.

9. "The credentials did not work" specifically

This message usually means the credentials reached the server but were rejected. Causes:

  • Typo in password (caps lock?)
  • Wrong domain (your laptop's local user vs. your AD user)
  • Password expired — check elsewhere if you can log in to the same account

10. Black screen after connecting

Successful connection but the desktop is black:

  • Press Ctrl + Alt + End (RDP's version of Ctrl + Alt + Del)
  • This usually un-stalls the session
  • If not, the target's graphics driver may have crashed — restart the target

When to ticket

Raise a ticket if:

  • VPN is connected and you still can't reach the target
  • The target is a server you're supposed to have access to but doesn't list you
  • "The remote computer requires Network Level Authentication" persists after client update

Include the target hostname or IP, your username (without the password), what error message you see verbatim, and what you've tested.