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I connect to the Internet using a DSL modem and service from Verizon. For security, and to share the connection between home computers, I added a D-Link DI-624 wireless router after the DSL modem as a hardware firewall. It covers two roles. It is a router, working as a DHCP server to distribute local addresses with firewall and filtering options, and a wireless access point for wireless clients. I have one computer directly connected to one of the wireless router LAN ports for configuration and firmware upgrades. A laptop can connect wirelessly. You can read my Mac OS X and Windows Wireless Network article for more information on the setup.
After upgrading to the latest firmware and resetting all my configuration options, I found I could not connect to Web pages on Internet sites. I found I could still connect if I moved my computer's ethernet cable to the DSL modem and switching to PPPoE. I needed to review the documentation for firmware upgrade, basic setup, and DSL/PPPoE setup and assemble other resources in preparation for troubleshooting. I have a mix of MacOS X and Windows computers on my home network. The configuration computer is a Mac. The process of finding the problem is the same but the application windows differ between Windows and Mac.
First, I needed to become informed. I browsed the D-Link support resources for the unit and downloaded the PDF user manual and an archive of FAQs. Since I'm troubleshooting my Internet connection, I wanted to have local reference material.
There were a number of files I wanted locally for off-line reference. I created a notes file with details on the equipment, settings, and procedures from my online research. I downloaded the wireless router user manual, a zip file of all the FAQs, and the latest firmware file. Note, the FAQ is one long page covering many products but does have illustrations. Naturally, all instructions assume you are a Windows user. The Web admin interface for the router is the same on both platforms. Be aware that linked text in the downloaded "All FAQs" page may point to resources on the D-Link Web site.
In addition, I needed to have several applications open and available during the troubleshooting. On MacOS X, I needed:
While the home network has a couple of computers, the simplest hardware setup for troubleshooting includes the DSL modem, the D-Link DI-624 Wireless Router, and one computer directly-cabled to a router port. The last is also required if you wish to upgrade firmware. This setup wouldn't test wireless availability of course. I could disconnect the cable and switch to Airport as the Mac has an internal Airport wireless card to test that.
It is a good idea to get label information from your hardware as you might need it for technical support. My DSL modem has manufacturer and model name, full model number, serial number, and an assembled date. The DI-624 label has the full model name, hardware revision number (needed for the correct support site information), original firmware version and the MAC number (a unique hardware ID.) You can get the router's current firmware version from the Status:Device Info screen. It will also list the router MAC address (under LAN) and the DSL modem MAC address (under WAN). Technical support also likes to know what platform (Mac, Windows, or Linux) and operating system version (MacOS X, Windows XP, etc.) you are using and what wireless adapter you are using.
While testing, it is helpful to watch the indicator lights on the DSL modem and the wireless router:
Some documents recommended power-cycling the DSL modem and wireless router as one way to reset or refresh a connection. Here are a couple of the steps from setting up a DSL modem and wireless router after entering the PPPoE settings in the Home:WAN screen:
Step 8: Click the "Apply" button and when prompted on the next screen, click Continue. Once the screen refreshes to the settings window again, unplug the power to the D-Link router.
Step 9: Turn off your DSL modem for 2-3 minutes... Turn back on. Once the modem has established a link to your ISP ("Ready" light stops blinking), plug the power back into the D-Link router. Wait about 30 seconds and log back into the router's admin screens at 192.168.0.1.
It is always handy to know how to get back to a pre-installation state and then re-trace installation steps to verify configuration. The initial quick installation guide states the following after connecting power to your router:
1. Power off your Cable or DSL modem; some devices may not have a on/off switch and will require you to unplug the power adapter. Now, the DI-624 should be powered on and the Cable/DSL modem should be turned off.
2. Cable / DSL modem (Power Off) - DI-624 (Power On) Connect an Ethernet cable to the Ethernet jack located on the Cable / DSL modem. After the Ethernet cable is securely connected, power on the Cable / DSL modem by turning on the unit or plugging in the power adapter.
3. Cable / DSL modem (Power On) - DI-624 (Power On) Insert the other end of the Ethernet cable to the WAN PORT on the back panel of the DI-624. The WAN LED light will illuminate to indicate proper connection.
Note, both upgrading the firmware or manually resetting the router, by inserting a paper clip in the reset hole on the back of the router for 10 seconds while powered, will return all settings to factory defaults. (The router's Tools:System screen also has an "Restore To Factory Default Settings" option.) You will need to reconfigure, entering your DSL/PPPoE information.
Most testing and all configuration are done via the wireless router Web interface at http://192.168.0.1/ after login with admin username and password. In my research, reading, and speaking to tech support, I identified several screens that are useful.
I found that, while the connection problem existed, using this ping test gave a successful result but the a similar ping test from the command-line in Terminal or the Network Utility gave problem results. Double-check your tests. Once the problem resolved, all three gave similar successful results.
Additionally, you can open a DOS window (Start:Run:cmd) or a Terminal window on MacOS X (Applications:Utilities:Terminal). Check if your computer has a LAN IP address (192.168.x.x), and then 'ping' local and Internet IP addresses:
If you succeed with the local router ping but not the Internet address ping, reboot the router (Tools:Misc.)
Additionally, you can use traceroute to track the hops along a path to a remote server. On Windows, the command is "tracert" and you can tell it to not resolve IP addresses to host names with "-d", if desired (a bit faster.) On MacOS X, or any Unix flavor, use "traceroute" and "-n" to not resolve addresses. This command is handy if one or more computers can get to the Internet but one cannot.
You can use the IP addresses retrieved with ping on the problem computer. (Also, traceroute.org allows you to run a trace from a remote server to your computer.)By the way, in Spring 2006, I found I could no longer use traceroute successfully on my MacOS X Jaguar (10.2.8) computer. My Windows XP Dell had no trouble at all. On MacOS X, I would get the router address, 192.168.0.1, but only "stars" for the other hops until it timed out. Perhaps something changed on the Verizon routers. Traceroute normally uses UDP packets. You have the option of switching to ICMP (ping) packets by using a command-line switch, "-I". While MacOS X Tiger (10.4) now has that option, the Jaguar (10.2) and Panther (10.3) version of traceroute do not. Note, the MacOS X Network Utility and third-party WhatRoute utilities are graphical interfaces to the underlying command. I could not compile the "mtr" executable, mentioned in some articles. I did find the Sustainable Softworks IPNetMonitorX utility's traceroute successful.
I found I could connect and browse Internet Web sites successfully while in direct PPPoE mode. When including the router, I received a good LAN address for my client computer and I found the admin screens showed I successfully connection to the Verizon servers, displaying an Internet WAN address. I found I could ping a numerical IP address but not a host name. This identified the problem as DNS resolution.
The DI-624 documentation suggests using the router's gateway IP address, 192.168.0.1, if your client is using a static IP address, rather than DHCP. This was confirmed by D-Link tech phone support. From the PDF user manual under "Networking Basics: Assigning a Static IP Address in Windows XP/2000":
Input your DNS server addresses. (Note: If you are entering a DNS server, you must enter the IP Address of the Default Gateway.)
One tech recommended static IP addresses for non-laptop home computers. In this case, in addition to entering the router gateway address in the Primary DNS Server field in the Home:WAN router admin setup screen, you also need to have it in the client DNS primary server field. As an option in both the admin screen and my OS TCP/IP setup screen, I also included 4.2.2.2 as the secondary DNS server.
In the category of "things I didn't know", I discovered in speaking to one of the techs that the DHCP server in the router distributes addresses in the '.100' to '.199' address range. Therefore, if you use a static address, use values below 100. He preferred beginning assignments in the lower range (Ex: 192.168.0.5)
I also made a couple other changes in the router's admin screens:
Also, on more than one site I visited, I saw the recommendation to use my vendor's wireless adapter utility over the Windows Wireless Network Connection utility available in XP/SP2, often called the Wireless Zero Configuration (WZC) utility. That utility runs as a service at startup and will place a small icon in the system tray at lower right on the task bar. The technician suggested disabling Windows handling wireless connections (a default in XP) in favor of using the vendor utility. From my collected notes after reviewing "WZC Service may create problems with WiFi adapters" article:
If you right-click on the WZC icon, options in the menu include: Disable; Repair, and View Wireless Networks. "Repair" is very handy for troubleshooting and refreshing settings. It will disable and then enable the wireless adapter, connect to the network, refresh the IP address, clear cache, and re-register with DNS. [Repair is unavailable on a limited user account as it requires, by design, administrative privileges.]
You can double-click the WZC icon in the system tray, click "View Wireless Networks" and select "Change advanced settings" in the left panel. Select the "Wireless Networks" tab to uncheck the "Use Windows..." box mentioned here. (If WZC service is not running, you will NOT see the "Wireless Networks" tab under "advanced settings".)
Wireless Zero Configuration [WZC] needs to be running as a service to access this. Verify the service by opening Start:Control Panel:Administrative Tools:Services, scrolling to Wireless Zero Configuration to see if the service is "Started" and startup is "Automatic". (These are the default settings.) You can change values after double-clicking the service.
Now that I have the Internet connection problem solved for one computer, I should test other possible setups I might use.
So, what was the problem? Perhaps a combination of using DHCP dynamic range addresses as static addresses, incorrect or inconsistent DNS entries in both the router and client configurations, a less-than-optimal MTU setting and the fact that the default channel, 6, wasn't the best choice. My settings worked before but perhaps the firmware change highlighted the inefficiencies.
I spent the better part of three days troubleshooting this problem, mostly on my own. I read much documentation and visited a number of Web pages. When I finally contacted tech support with a log of notes and options tried, it still took several tries. I found a solution after the problem was escalated to a "Level 2" support request. Working with that tech, I had a solution in 10 minutes.
In pondering this troubleshooting episode, I think of how difficult it is to self-support your computer environment and also how hard it is to find talented support professionals, who can get the job done in 10 minutes. In any case, I hope this page helps someone else to troubleshoot their non-performing setup.