Troubleshooting a Wireless VPN Connection

I've got a wireless computer and a VPN client. I've followed all the client installation steps, but I can't seem to connect.

The first six steps are simple checks that any users can perform. The others are more suited for advanced users and IT professionals.

Simple troubleshooting

1. (For removable wireless cards) Is your wireless card correctly installed?
   If you have a removable wireless card, make sure sure that your card is fully inserted into its slot, and that your hardware and software both recognize the card's presence. See your card software's help instructions for self-test procedures.
   
   
2. Have you configured it for use on UIUCnet Wireless?
   The SSID (also called Network Name, the name used to identify which wireless network your're accessing) is UIUCnet.
   
   
3. If your card has an activity light, does the light flash the correct color to indicate successful activity?
   Many cards flash a green light to indicate that activity is possible. Again, check your card's instructions for product-specific details.
   
   
4. Does your wireless software report that it is associated with an access point?
   If not, move to an area closer to one of the access points (listed on the Locations page).
   
   
5. Are you receiving any specific error messages from your software?
   If so, check the documentation for that software for further assistance. (If the error message is about an incorrect password, check with the Help Desk at 244-7000 about whether you remember your password correctly or should change it.)
   
   
6. Do you have the Intel 3945 WiFi driver?
   Some Windows laptops come with software that causes known connection problems. See Troubleshooting the Intel 3945 WiFi driver for more information.

Advanced troubleshooting

Note: If you don't feel comfortable with these advanced troubleshooting steps, contact the Help Desk at DCL 1211, consult@illinois.edu, or 244-7000.

1. Once your wireless software reports association with an access point, is the access point's address in the range of 172.21.0.1 to 172.21.15.254?
   If the access point your card has connected to is not within that range, the access point you're using is not one associated with the University network. Again, move closer to one of the access points (listed on the Locations page).
   
   
2. Is your machine configured to use DHCP?
   DHCP (Dynamic Host Configuration Protocol) allows servers to assign temporary network IP addresses to computers that contact them and ask for an identity. On a Windows system, this is usually described with the "Obtain an IP address automatically" option. On a Macintosh this is described with the "Configure using DHCP server" option, available in the TCP/IP properties of the network adapter. In order to access the wireless network at UIUC with the VPN server, your machine will need to be configured to use DHCP.
   

Configuring DHCP on a Windows machine

Go to Start -> Programs -> Accessories -> Communications -> Dialup Networking (or Network and Dialup Connections), then selecting the connection you want to examine. Right-click on the connection you use and choose Properties. In the Properties dialogue box, select the TCP/IP item and click Properties.

One of the DNS options listed should be Obtain an IP address automatically (or wording to that effect). You want to obtain an IP address from the DHCP servers, so make sure that option is selected. Then click OK until you've returned to the desktop. (You may need to reboot your machine.)

On a Mac OS X machine:

Go to the Apple menu, then System Preferences, then click the Network button, then the TCP/IP tab.

Depending on your machine's configuration, you may need an administrative password (or someone who knows it) to tell the machine to get its IP address from a DHCP server.

Once you've accomplished this, click OK until you've returned to the desktop. (You may need to reboot your machine.)

3. Once you're close enough to an access point to connect, your machine is configured to use DHCP, and you've established a connection through the VPN client, did your machine receive an IP address in the range of 192.17.144.25 to 192.17.147.250?

To check this on Windows 2000, XP, and Vista machines:

Click Start, then Run. In the window that appears, type cmd

In the DOS window that opens, type ipconfig

Within the same window, networking information will be displayed.

To check this on Macintosh OS X machines:

Click the Apple menu, then Location, then Network Preferences.

The system should identify the IP address assigned and the way it was assigned (by the DHCP server).

If you successfully connected to the DHCP server, you should see information for the DHCP server, a number in the range of 172.21.8.x - 172.21.15.254 for the IP address, and the default gateway should be set to 172.21.0.1.

If you did not receive an IP address in this range, there are three possibilities:
1) The network card isn't working.
2) You aren't properly associated with an access point (see basics 4 and 5 above).
3) The DHCP server didn't answer your machine.

If you've established that you are correctly associated with an access point that belongs to the UIUC domain, try rebooting your system. If you still can't connect, contact the Help Desk at DCL 1211, consult@illinois.edu, or 244-7000.

4. Can you ping 172.21.0.22 or 128.174.1.99?
   Click Start, then Run. In the window that appears, type cmd

   In the DOS window that opens, type:
   
   ping 172.21.0.22

   In the text that follows, you should see a message like the following:
   
   Packets: Sent = 4, Received = 4, Lost = 0 (0% loss
   Approximate round trip times in milli-seconds:
   Minimum = 0ms, Maximum = 0ms, Average = 0ms


If the message indicates that some packets were lost, contact the Help Desk at DCL 1211, consult@illinois.edu, or 244-7000. There may be a configuration problem with your VPN client, or there may be network trouble.


5. If none of the above steps have helped:
   For further assistance, contact the Help Desk at DCL 1211, consult@illinois.edu, or 244-7000.