D Link DIR855A1 User Manual

Section 6 - Troubleshooting

Troubleshooting

This chapter provides solutions to problems that can occur during the installation and operation of the DIR-855. Read
the following descriptions if you are having problems. (The examples below are illustrated in Windows® XP. If you have
a different operating system, the screenshots on your computer will look similar to the following examples.)

1. Why can’t I access the web-based configuration utility?

When entering the IP address of the D-Link router (192.168.0.1 for example), you are not connecting to a website on
the Internet or have to be connected to the Internet. The device has the utility built-in to a ROM chip in the device itself.
Your computer must be on the same IP subnet to connect to the web-based utility.

• Make sure you have an updated Java-enabled web browser. We recommend the following:

• Internet Explorer 6.0 or higher

• Netscape 8 or higher

• Mozilla 1.7.12 (5.0) or higher

• Opera 8.5 or higher

• Safari 1.2 or higher (with Java 1.3.1 or higher)

• Camino 0.8.4 or higher

• Firefox 1.5 or higher

• Verify physical connectivity by checking for solid link lights on the device. If you do not get a solid link light, try using
a different cable or connect to a different port on the device if possible. If the computer is turned off, the link light may
not be on.

• Disable any internet security software running on the computer. Software firewalls such as Zone Alarm, Black Ice,
Sygate, Norton Personal Firewall, and Windows® XP firewall may block access to the configuration pages. Check the
help files included with your firewall software for more information on disabling or configuring it.

81D-Link DIR-855 User Manual

Section 6 - Troubleshooting

• Configure your Internet settings:

• Go to Start > Settings > Control Panel. Double-click the Internet Options Icon. From the Security tab,

click the button to restore the settings to their defaults.

• Click the Connection tab and set the dial-up option to Never Dial a Connection. Click the LAN Settings
button. Make sure nothing is checked. Click OK.

• Go to the Advanced tab and click the button to restore these settings to their defaults. Click OK three
times.

• Close your web browser (if open) and open it.

• Access the web management. Open your web browser and enter the IP address of your D-Link router in the address
bar. This should open the login page for your the web management.

• If you still cannot access the configuration, unplug the power to the router for 10 seconds and plug back in. Wait
about 30 seconds and try accessing the configuration. If you have multiple computers, try connecting using a different
computer.

2. What can I do if I forgot my password?

If you forgot your password, you must reset your router. Unfortunately this process will change all your settings back
to the factory defaults.

To reset the router, locate the reset button (hole) on the rear panel of the unit. With the router powered on, use a
paperclip to hold the button down for 10 seconds. Release the button and the router will go through its reboot process.
Wait about 30 seconds to access the router. The default IP address is 192.168.0.1. When logging in, the username is
admin and leave the password box empty.

82D-Link DIR-855 User Manual

Section 6 - Troubleshooting

3. Why can’t I connect to certain sites or send and receive emails when connecting through my router?

If you are having a problem sending or receiving email, or connecting to secure sites such as eBay, banking sites, and
Hotmail, we suggest lowering the MTU in increments of ten (Ex. 1492, 1482, 1472, etc).

Note: AOL DSL+ users must use MTU of 1400.

To find the proper MTU Size, you’ll have to do a special ping of the destination you’re trying to go to. A destination could
be another computer, or a URL.

• Click on Start and then click Run.

• Windows® 95, 98, and Me users type in command (Windows® NT, 2000, and XP users type in cmd) and

press Enter (or click OK).

• Once the window opens, you’ll need to do a special ping. Use the following syntax:

ping [url] [-f] [-l] [MTU value]

Example: ping yahoo.com -f -l 1472

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Section 6 - Troubleshooting

You should start at 1472 and work your way down by 10 each time. Once you get a reply, go up by 2 until you get a
fragmented packet. Take that value and add 28 to the value to account for the various TCP/IP headers. For example,
lets say that 1452 was the proper value, the actual MTU size would be 1480, which is the optimum for the network
we’re working with (1452+28=1480).

Once you find your MTU, you can now configure your router with the proper MTU size.

To change the MTU rate on your router follow the steps below:

• Open your browser, enter the IP address of your router (192.168.0.1) and click OK.

• Enter your username (admin) and password (blank by default). Click OK to enter the web configuration

page for the device.

• Click on Setup and then click Manual Configure.

• To change the MTU enter the number in the MTU field and click Save Settings to save your settings.

• Test your email. If changing the MTU does not resolve the problem, continue changing the MTU in
increments of ten.

84D-Link DIR-855 User Manual

Appendix A - Wireless Basics

Wireless Basics

D-Link wireless products are based on industry standards to provide easy-to-use and compatible high-speed wireless
connectivity within your home, business or public access wireless networks. Strictly adhering to the IEEE standard,
the D-Link wireless family of products will allow you to securely access the data you want, when and where you want
it. You will be able to enjoy the freedom that wireless networking delivers.

A wireless local area network (WLAN) is a cellular computer network that transmits and receives data with radio signals
instead of wires. Wireless LANs are used increasingly in both home and office environments, and public areas such
as airports, coffee shops and universities. Innovative ways to utilize WLAN technology are helping people to work and
communicate more efficiently. Increased mobility and the absence of cabling and other fixed infrastructure have proven
to be beneficial for many users.

Wireless users can use the same applications they use on a wired network. Wireless adapter cards used on laptop
and desktop systems support the same protocols as Ethernet adapter cards.

Under many circumstances, it may be desirable for mobile network devices to link to a conventional Ethernet LAN in
order to use servers, printers or an Internet connection supplied through the wired LAN. A Wireless Router is a device
used to provide this link.

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Appendix A - Wireless Basics

What is Wireless?

Wireless or Wi-Fi technology is another way of connecting your computer to the network without using wires. Wi-Fi
uses radio frequency to connect wirelessly, so you have the freedom to connect computers anywhere in your home or
office network.

Why D-Link Wireless?

D-Link is the worldwide leader and award winning designer, developer, and manufacturer of networking products.
D-Link delivers the performance you need at a price you can afford. D-Link has all the products you need to build your
network.

How does wireless work?

Wireless works similar to how cordless phone work, through radio signals to transmit data from one point A to point
B. But wireless technology has restrictions as to how you can access the network. You must be within the wireless
network range area to be able to connect your computer. There are two different types of wireless networks Wireless
Local Area Network (WLAN), and Wireless Personal Area Network (WPAN).

Wireless Local Area Network (WLAN)

In a wireless local area network, a device called an Access Point (AP) connects computers to the network. The access
point has a small antenna attached to it, which allows it to transmit data back and forth over radio signals. With an
indoor access point as seen in the picture, the signal can travel up to 300 feet. With an outdoor access point the signal
can reach out up to 30 miles to serve places like manufacturing plants, industrial locations, college and high school
campuses, airports, golf courses, and many other outdoor venues.

86D-Link DIR-855 User Manual