Diagnose and Overcome a Network Connectivity Problem


By: PsychoTeddy
December 20, 2010

It is one of the most frustrating things that can happen to anyone.  Plugging in your computer expecting to see a nice, shiny, welcome homepage with arms outstretched, you have the door slammed in your face with the task bar shouting that it cannot find a network connection.  Enfuriated, you begin contemplating ways to send the infernal object of torment perched upon your desk to the very lowest, hottest place in Hades. 

Not to fret, following some of the guidelines in this guide, I hope to have you back up and running in no time.

99% of all network problems are caused by two things:

1. Bad configuration

2. Bad components

Preface:

I know that these steps may seem elementary but even the pros make these mistakes from time to time.  Make sure that your router, modem, and laptop are plugged in an appear to be working before going through this list.  You may spend hours trying to find the problem when you've overlooked the fact that your dog chewed through your ethernet cable and nothing has gone horribly wrong in the first place.

I. Configuration:

Configuration settings can be both the easiest and most difficult route to solving your networking woes.  From something as simple as a static IP left in the settings menu, to discovering a DNS hi-jacking, it covers a wide range of possibilities. 

A. IP Addressing Problems

IP address conflicts and misconfigurations are the most common source of network connectivity problems.  Inexperienced users and network gremlins have a nasty habit of going in and changing settings that can have a strong impact on how networks operate and perform. 

1. IPv6:

IPv6 is a new IP addressing scheme designed to allow for more computers on large networks.  Unfortunately, IPv6 has yet to be widely implemented and has major compatibility problems.  I generally start troubleshooting by disabling IPv6 because it is a simple, two second fix that solves the problem around 30-40% of the time in my experience.  To disable IPv6:

  • Control Panel
  • Network and Sharing Center
  • Change Adapter Settings
  • Right Click the Connection You're Using
  • Properties
  • Uncheck IPv6
  • OK

Try to connect again and see if that works.

2. Static IP Address:

Another common problem with network connectivity is almost as simple as disabling IPv6.  Some people (or programs) will setup a static IP address which forces the network to give your computer a certain address when the router refuses to (either because of network policy or because another system is using that address).

  • Control Panel
  • Network and Sharing Center
  • Change Adapter Settings
  • Right Click the Connection You're Using
  • Properties
  • IP Version 4
  • Properties
  • Automatically obtain an IP address
  • Automatically obtain DNS server addresses
  • OK
  • OK

Try to connect again and see if that works.

3. Winsock fix:

Sometimes settings behind the scenes are changed and need to be reset.  The winsock fix provides this capability.

  • Start
  • Run...
  • Type cmd
  • OK
  • type netsh winsock reset catalog
  • Enter

Try to connect again and see if that works.

4. Make Sure That Your Adapters are Enabled:

Sometimes adapters will become disabled for no apparent reason.  It just happens.

  • Control Panel
  • Network and Sharing Center
  • Change Adapter Settings
  • Right Click Your Connection
  • Enable

If the menu says "Disable", your adapter is enabled and requires no further action for this step.

5. Disable Your Firewall

Your firewall may have something to do with the reason that your computer cannot connect to your network.  Unfortunately, this guide would have to cover every single firewall in order to be effective.  Contact your security suite's manufacturer to receive instructions on how to configure your security software to allow you to connect to your network.

6. DHCP

DHCP allows your router to assign IP addresses automatically.  Go into your router's settings and make sure that this feature is ON.

B. Wireless Troubleshooting

If you're trying to connect with a wireless network, there are a few other steps that you can try in addition to the ones above (yes, go through those FIRST) to try to connect again.

1. Distance From the Router:

A very common problem with wireless networking is that, people tend to think that just because they have one bar of service, they can connect to the router.  This is not always the case.  Simply try moving closer to the router and see if you can connect.

2. Power Savings:

Another common problem with wireless networking is with power savings features on some WLAN adapters.  Disabling these power savings by changing your power management policy in Windows is another basic step to take.

  • Control Panel
  • Power Settings
  • High Performance Power Profile
  • Save

3. Router Channel:

Most routers operate in or around the 2.4GHz wavelength for wireless networks.  However, small changes to the frequency can reduce interference whilst still allowing devices to connect to it (a situation where close counts in something other than horseshoes and hand grenades).  In your router's settings, you should be able to find something pertaining to a channel.  Select something else and click save.  Try this a couple times to see if it works.

4. Router Positioning:

Make sure that your router is sitting/mounted somewhere high away from all sources of EMI (Electromagnetic Interference).  Sources of EMI include (but are not limited to): Microwaves, Other computers, Other routers, Cell phones, Speakers, Monitors, Headphones, Little Sisters.  Also, include it in a central location in your house where you have to transmit through as few walls and obstacles as possible.

5. Router Heat:

Routers can become quite warm and ventilation is always a concern.  This affects wired performance, but absolutely murders wireless performance. Feel the bottom of your router with your hand.  It is permissible for it to be slightly warmer than room temperature, but if it's toasty or on fire you may want to consider better ventilation or positioning.  Carpet, heater vents, etc are all sources of heat that should be kept far away from your router.

II. Components

A. Cables

Bad cables are very hard to diagnose for the lay user.  The best solution is just to go out and buy a brand new cable.  If that doesn't work, it's ruled out.

B. Bad Ports

Ports may go bad on devices and are very hard to diagnose.  Best way to diagnose this is to see if activity lights on the port itself come on when another device or port is used.

C. ISP

A lot of times the problem doesn't even begin with YOUR network.  High latencies and overall crappy service can sometimes be the cause of your problems.  If you can get an IP address from your network, but can't get out to the internet and have followed all of these steps, it's time to harass your ISP.

I hope this helps and thank you for taking the time to read through all of this before posting the 10,000,000th "I CANT CONNECT OMG WTF" thread in the forums ;)


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