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Section 6 - Troubleshooting
Troubleshooting
This chapter provides solutions to problems that can occur during the installation and operation of the DIR-857. 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 
• Chrome 2.0 or higher 
• Safari 3.0 or higher 
• Firefox 3.0 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.  
						

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• 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.  
						

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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, XP, Vista® and 7 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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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. 
   
						

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Appendix A - 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.
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.  
						

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Appendix A - Wireless Basics
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, 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.
Wireless Personal Area Network (WPAN)
Bluetooth is the industry standard wireless technology used for WPAN. Bluetooth devices in WPAN operate in a range up to 30 feet away.
Compared  to WLAN  the  speed  and  wireless  operation  range  are  both  less  than WLAN,  but  in  return  it  doesn’t  use  nearly  as  much  power  which 
makes it ideal for personal devices, such as mobile phones, PDAs, headphones, laptops, speakers, and other devices that operate on batteries.
Who uses wireless? 
  
Wireless  technology  as  become  so  popular  in  recent  years  that  almost  everyone  is  using  it,  whether  it’s  for  home,  office,  business,  D-Link  has  a 
wireless solution for it.
Home
  • Gives everyone at home broadband access
  • Surf the web, check email, instant message, and etc
  • Gets rid of the cables around the house
  • Simple and easy to use
 
Small Office and Home Office
  • Stay on top of everything at home as you would at office
  • Remotely access your office network from home
  • Share Internet connection and printer with multiple computers
  • No need to dedicate office space
   
						

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Where is wireless used? 
  
Wireless technology is expanding everywhere not just at home or office. People like the freedom of mobility and it’s becoming so popular that more 
and more public facilities now provide wireless access to attract people. The wireless connection in public places is usually called “hotspots”.
Using a D-Link Cardbus Adapter with your laptop, you can access the hotspot to connect to Internet from remote locations like: Airports, Hotels, 
Coffee Shops, Libraries, Restaurants, and Convention Centers.
Wireless network is easy to setup, but if you’re installing it for the first time it could be quite a task not knowing where to start. That’s why we’ve put 
together a few setup steps and tips to help you through the process of setting up a wireless network.
Tips
Here are a few things to keep in mind, when you install a wireless network.
Centralize your router or Access Point
  
Make sure you place the router/access point in a centralized location within your network for the best performance. Try to place the router/access 
point as high as possible in the room, so the signal gets dispersed throughout your home. If you have a two-story home, you may need a repeater 
to boost the signal to extend the range.
Eliminate Interference 
  
Place home appliances such as cordless telephones, microwaves, and televisions as far away as possible from the router/access point. This would 
significantly reduce any interference that the appliances might cause since they operate on same frequency.
Security 
  
Don’t  let  you  next-door  neighbors  or  intruders  connect  to  your  wireless  network.  Secure  your  wireless  network  by  turning  on  the WPA  security 
feature on the router. Refer to product manual for detail information on how to set it up.  
						

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Appendix A - Wireless Basics
There are basically two modes of networking:  • Infrastructure – All wireless clients will connect to an access point or wireless router.
•  Ad-Hoc – Directly connecting to another computer, for peer-to-peer communication, using wireless network adapters on each 
computer, such as two or more DIR-857 wireless network Cardbus adapters.
An Infrastructure network contains an Access Point or wireless router. All the wireless devices, or clients, will connect to the wireless router or access 
point. 
An  Ad-Hoc  network  contains  only  clients,  such  as  laptops  with  wireless  cardbus  adapters.  All  the  adapters  must  be  in  Ad-Hoc  mode  to 
communicate.
Wireless Modes  
						

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Appendix B - Networking Basics
Networking Basics
Check your IP address
After  you  install  your  new  D-Link  adapter,  by  default,  the TCP/IP  settings  should  be  set  to  obtain  an  IP  address  from  a  DHCP  server  (i.e.  wireless 
router) automatically. To verify your IP address, please follow the steps below.
Click on Start > Run. In the run box type cmd and click OK. (Windows® 7/Vista® users type cmd in the Start Search box.)
At the prompt, type ipconfig and press Enter.
This will display the IP address, subnet mask, and the default 
gateway of your adapter.
If the address is 0.0.0.0, check your adapter installation, security 
settings, and the settings on your router. Some firewall software 
programs  may  block  a  DHCP  request  on  newly  installed 
adapters. 
If you are connecting to a wireless network at a hotspot (e.g. 
hotel,  coffee  shop,  airport),  please  contact  an  employee  or 
administrator to verify their wireless network settings.  
						

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Appendix B - Networking Basics
Statically Assign an IP address
If you are not using a DHCP capable gateway/router, or you need to assign a static IP address, please follow the steps below:
Step 1
Windows® 7 - Click on Start > Control Panel > Network and Internet > Network and Sharing Center.
Windows Vista® - Click on Start > Control Panel > Network and Internet > Network and Sharing Center > Manage Network Connections.
Windows XP - Click on Start > Control Panel > Network Connections.
Windows 2000 - From the desktop, right-click My Network Places > Properties.
Step 2
Right-click on the Local Area Connection which represents your D-Link network adapter and select Properties.
Step 3
Highlight Internet	Protocol	(TCP/IP) and click Properties.
Step 4
Click  Use the following IP address and enter an IP address that is on the same subnet as your network 
or the LAN IP address on your router. 
Example: If the router´s LAN IP address is 192.168.0.1, make your IP address 192.168.0.X where X is a 
number between 2 and 99. Make sure that the number you choose is not in use on the network. Set 
Default Gateway the same as the LAN IP address of your router (192.168.0.1). 
Set Primary DNS the same as the LAN IP address of your router (192.168.0.1). The Secondary DNS is not 
needed or you may enter a DNS server from your ISP.
Step 5
Click OK twice to save your settings.