VPN 檢修及問答題

VPN Troubleshooting & FAQ

We have gathered a list of known issues and problems associated with the VPN, alternatively you can email our Service Desk

1. Will my ISP email account still work?
Probably not. Many ISPs restrict access to their email service to their own networks. As our VPN Service assigns you a private network IP address on top of your ISP-assigned IP address, it will appear to be coming from outside your ISP's trusted network and will be rejected. To continue using your ISP email service, simply disconnect from our VPN service and restart your ISP-provided email client. However, if you host your own email server at your office or at a data center, you will be able to access your email account freely with a VPN connection.

2. What services can I use across the Silverland VPN Service?
Our VPN service provides worldwide unblocked access to all international computer hosts.

3. I want to use my computer for purposes allowed by my ISP but not by Silverland's VPN Terms & Policy. What should I do?
Simply disconnect from our VPN Service. Network traffic will now route via your ISP as normal.

4. I have a Firewall on my Computer. What should I do?
Most firewalls by default will block VPN (or more strictly the PPTP network protocol used by our VPN Service). You normally have to enable your firewall to allow this traffic in order to use our VPN Service. Please consult your firewall manufacturer's documentation. If it asks for an address range then you should allow PPTP traffic to/from our VPN IP addresses:

Our VPN servers: 203.194.245.62

Our VPN service client IP address range:
192.168.10.10 / 255.255.255.0 ~ 192.168.10.255 / 255.255.255.0

We regret that because of the wide variety of firewall products now available we cannot offer specific advice on how to set up your firewall to allow the VPN Service. If in doubt, you may temporarily disable your firewall to see if you can successfully connect to our VPN service without a firewall.

NOTE: Problems have been reported when using Zone Labs ZoneAlarm products.

5. I have set up the VPN Client as instructed in the documentation but it still doesn't work. What should I do?

Verify your installation.
Check the rest of this FAQ to check for other answers.
Ensure that your operating system (Windows, Mac OS, Linux, etc.) is fully updated and patched.
Check with your ISP's Service Desk that its network will allow PPTP (Point to Point Tunneling Protocol) traffic. Some will not.
Contact our Service Desk with details of any error messages.

6. I've configured my web browser to use my ISP's web cache. Will it still work?
You may get some problems, e.g. delays in page loading and possibly problems with certain interactive sites. You may wish to disconnect your web browser from the ISP web cache for the duration of your VPN session to our network. You do not need to specify a cache as our VPN service will divert to it anyway. Reconnect your ISP web cache connection when finished with the VPN to restore the full range of services from your ISP.

7. I have a PDA. Can I use it with the VPN Service?
Possibly. There are 3rd-party VPN clients that support PPTP for Windows CE - although mainly for PocketPC. You may have to purchase a license. Please consult your PDA manufacturer for more information. While we will use our best endeavours to help get your PDA working with our VPN Service, we cannot guarantee success in all cases.

8. My VPN connection sometimes disconnects itself, why?
It may be due to heavy network traffic, e.g. at times of peak demand during weekends and evenings. Simply reconnect. If you work extensively off public WiFi connections and suffer regular disconnection then you may wish to consider relocating yourself to use another access point with a better internet connection.

9. I get a message telling me that there is a name conflict on the network, what does this mean?
If your computer has a name that is already in use by another computer on our network, you may get the error. You may ignore this and continue to use our VPN services without any problems.

10. I use a modem to dial my ISP automatically, and the VPN will not connect.
Some users have reported that if the option to "Dial the connection automatically" is used in the VPN setup, then the VPN connection fails - this issue was reported with AOL. Try connecting to your ISP manually, then opening the VPN connection.

11. The VPN connection is not working with Windows 95 and 98
An upgrade to the "Dial Up Networking" (DUN) service is available for these operating systems. You should download DUN 1.4 from Microsoft.

12. I am trying to use the VPN from behind a corporate firewall. What ports and protocols does the VPN use?
Many other (corporate or otherwise) may use a firewall to control network traffic out of their network. In order to gain access, the user must request that their local IT Support opens the following ports on their firewall:

Port 1723 / TCP (PPTP)
Protocol #47 (GRE)

13. I am using Windows XP SP1, and my VPN connection drops every 55 seconds.
Microsoft have identified this to be a problem with XP Service Pack 1, where Internet Connection Sharing is enabled. Please see Microsoft Support Article Q331816 for more information. Please also note that sharing your VPN connection between multiple computers is against our VPN policy, as a user of one of the other machines will be using our network under your username, not their own.

14. I try to connect and get Error 800, my security parameters are incorrect.

a) Check that under VPN properties, on the Networking tab, that the "Type of VPN" is set to Automatic or PPTP
b) Check that your personal firewall is set to allow VPN connections, or that your corporate firewall allows these connections.

This error will be seen from places which do not allow VPN connections.

15. When connected to the VPN, I cannot browse web pages outside the private network / the network performance drops significantly.
This is likely to be related to specific settings such as MTU / RWIN associated with your network connection. DSL Reports provide a utility which will check your connection is configured optimally: http://www.dslreports.com/tweaks

16. Cannot connect to the VPN through an Apple Airport.
You need to ensure that you are using Airport 2.0.4 or higher to connect to our VPN Service. Click the link below for more information.

Apple Support - AirPort 2.0.4: About Using AirPort With Point to Point Tunneling Protocol (PPTP)

17. What username should I use to connect to the VPN service / my username is "invalid".

You must ensure that you are using your provided username and password.

18. I have installed Windows XP Service Pack 2 (SP2) and now I cannot connect / the connection drops frequently.

Make sure you have installed the networking hotfix for Service Pack 2.