Cannot connect to VPN?

Cannot connect to VPN?

Image by ijmaki from Pixabay

Applies To

Students and Staff

Note: Connect from Mainland China

You may experience an unstable VPN connection and even fail to connect from mainland China even followed every step in this guide. In addition, you may have the same VPN configuration works perfectly in the past but suddenly no longer works.

Specially, you may receive errors such as (but not limited to) 'Error 789' / unable to download VPN profile / L2TP-VPN server did not respond.

In this case, you are suggested to register for VPN Add-on service as a workaround.


This section describes the most common VPN problem scenarios. Read carefully as it may save you lots of time troubleshooting.

  1. Using 'CUHK VPN' ?  Try 'SSL VPN'.

    Some places (e.g. hotels) may have CUHK VPN blocked.  Try using SSL VPN to workaround this issue.

  2. Some IT Services do not require VPN.

    Email, Zoom, Blackboard and MyCUHK do NOT require VPN.  Check our list if you are unsure if VPN is required for your case.

  3. Please register DUO 2-Factor Authentication (2FA) first.

    For students, DUO 2FA is required for connecting all VPN services.

    For staff, DUO 2FA is required for connecting SSL VPN and VPN Add-On Service*.

    To register your account for DUO 2FA, please refer to the user guide.

    * Starting from 2 Feb 2021, DUO 2FA is required for all VPN services for staff.

  4. If your are in mainland China, try VPN Add-On service.

    If you experience unstable VPN connectivity using SSL / IPSec VPN in mainland China, consider using VPN Add-on service.

  5. Try temporary disable anti-virus protection.

    Some anti-virus apps may block VPN connection by mistake. Try disabling them for a short while and see if the problem could be solved.  If so, consider switching your anti-virus app to the one provided by the ITSC.

  6. Connected to VPN but unable to browse Library resources?

    Please refer to Off-Campus Access to E-Resources page from Library for details.

  7. Connected to VPN but unable to access department resources?

    Please contact your departmental IT support.

Known VPN Errors

Check this section for solutions to common error messages that you may received.

  1. CUHK VPN - Error 720: A connection to the remote computer could not be established

    Refer to this knowledge article for solution.

  2. CUHK VPN - Error 718 / 'Remote computer did not respond in a timely manner' / 「遠端電腦並未及時回應」 / 「远程计算机不能及时反应」

    Refer to this knowledge article for solution.

  3. CUHK VPN - Error 691 / 'Access denied because username and/or password is invalid on the domain.'

    Please verify your username / password are correct.

    Your username should be your CUHK email address (Students: / Staff: and the password is your OnePass password.

    If you are adding the six-digit passcode, please make sure to get a new code every time.

  4. CUHK VPN - 'A certificate could not be found.' / 「找不到憑證」 / 「找不到证书」

    Refer to this knowledge article for solution.

  5. CUHK VPN - Keep showing 'Connecting to VPN' and waited forever

    This may happen in certain Windows 10 PCs.  Refer to this knowledge article for solution.

  6. SSL VPN - Wait forever, asking me username / password over and over again (Error -8949)

    Refer to this knowledge article for solution.

  7. SSL VPN - 'Fail to resolve Server name' or never prompted to enter username / password.

    This may happen in certain Mac using Kaspersky Endpoint Security.  Refer to this knowledge article for solution.

Your problem is not listed above?

Please send us an enquiry and provide a screenshot for further investigation.

#cannot #failed #fail #login #連唔到 #認證失敗