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This articles covers Fast Fixes to Wi-Fi Problems.
|Tip:||See also Wi-Fi (main article) and Wi-Fi How To|
- 1 Top Ten Fixes to Wi-Fi Problems
- 2 Wireless Access Point is more expensive than Wireless Router
- 3 Don't do Double NAT
- 4 Can't connect to Wi-Fi client bridge and Internet at the same time
- 5 Poor coverage or range (weak signal)
- 6 Wireless connection drops periodically
- 7 Slow wireless speed
- 8 Too much wireless (RF) interference
- 9 Can't connect to the Internet
- 10 Can't connect to wireless router or access point
- 11 Internet isn't working
- 12 DHCP isn't working
- 13 Getting Windows Remote Desktop to work
- 14 Accidentally connecting to neighbor's Wi-Fi
- 15 Works with no security, but won't work with WEP
- 16 Wake On LAN (WOL) won't work from the Internet
- 17 Wireless router locks up and has to be restarted
- 18 IPCONFIG fails
Top Ten Fixes to Wi-Fi Problems
|10.||Upgrade Wi-Fi products to latest firmware.|
|9.||Try older firmware in Wi-Fi products.|
|8.||Reinstall all drivers.|
|7.||Get bigger/better antenna(s).|
|6.||Replace 2.4 GHz cordless phones with 900 MHz or 5 GHz phones.|
|5.||Don't use microwave oven & Wi-Fi at the same time.|
|4.||If there's a municipal wireless network, give up now.|
|2.||Throw out everything and start over with new stuff.|
|1.||Good, fast, cheap. Pick (at most) two.|
Now on to the serious stuff ...
Wireless Access Point is more expensive than Wireless Router
Don't do Double NAT
When adding wireless access to a wired network, as in the diagram at the right, be careful not to create double NAT problems. Since the wired router already has NAT, use either:
- a wireless access point (with no NAT) instead of a wireless router (with NAT), or
- a wireless router setup as a wireless access point.
See also "Configure a Network with Multiple Routers" in Answering Some Common Windows XP Home Networking Questions
Can't connect to Wi-Fi client bridge and Internet at the same time
In network terms, a bridge is transparent, passing data from each side to the other side (wireless to wired, wired to wireless). Thus in normal operation it doesn't have any use for IP addresses, just MAC addresses.
However, because of the need to manage Wi-Fi operation (SSID selection, WEP/WPA security, etc.), a Wi-Fi client bridge will typically have configuration screen(s) at a specified private IP address (e.g., 192.168.0.254) that can be accessed with a standard Web browser (e.g., Microsoft Internet Explorer) from a local computer. Unfortunately, unlike with a Wi-Fi router, a computer connected to a Wi-Fi client bridge can't normally communicate with both the client bridge configuration and the Internet at the same time. To deal with this problem, see How To Configure a Wi-Fi client bridge.
Poor coverage or range (weak signal)
Reduce possible interference
Better antenna (which helps both sending and receiving)
- Do It Yourself
- See How To Make a Wi-Fi antenna or reflector for cheap
- Really works!
- Can help even when antenna isn't replaceable
- See How To Make a Wi-Fi antenna or reflector for cheap
- Commercial replacement antenna (some, but not all, products have replaceable antennas)
- See Wi-Fi Antennas
Amount of antenna improvement
- Standard "rubber duck" antenna gain (effectiveness) is about 2 dBi.
- It takes an increase of 6 dBi to double range. Thus:
Antenna: 2 dBi 8 dBi 14 dBi etc. Range: 1x 2x 4x ...
"High gain" Wi-Fi adapter
Increase transmit power
- Won't help on receiving, so higher power may well be needed at both ends.
- Takes a lot more power to make a substantial difference in range.
- May increase interference to other users of the frequency band.
- Improving antenna (helping sending & receiving) is usually more effective & neighborly.
Add additional wireless Access Point(s)
Switch to MIMO products
- Greatly increased range/speed over standard Wi-Fi
- Must be same kind of MIMO at both ends to get any benefit
- Current MIMO products are proprietary, may not be compatible with eventual 802.11n standard
Wireless connection drops periodically
- Possible interference -- see Too much wireless (RF) interference
- Weak signal -- weaker than you think -- see #Don't trust Windows signal strength or speed
- Try manufacturer's wireless connection manager -- If your hardware came with its own wireless connection manager, trying installing and configuring it to manage wireless connections. (Some drivers will not maintain the association with the strongest signal access point in situations with high density access points.)
Don't trust Windows signal strength or speed
Even when signal is weak, Windows may report a good signal upon initial connection:
A bit later, more accurate signal is reported, but Windows is still reporting full 802.11g speed:
In this case the signal was so weak the connection would not work, and was soon lost.
The problem isn't Windows itself, but the wireless device driver from the wireless vendor -- Windows is just reporting what the driver tells it.
In addition, this doesn't tell you anything at all about signal quality and the amount of interference, which are as important as signal strength.
Moral: Don't trust signal strength or speed as reported by Windows. You may (or may not) get more accurate information from the wireless manufacturer's connection manager, or a tool like Network Stumbler (NetStumbler) instead.
May not actually be Connected
|Windows may show Wi-Fi
as being connected...
when it doesn't actually
- DHCP failure (interference and/or weak signal, broken DHCP server, or problem with Windows Vista DHCP client).
- Initial connection with wrong WEP or WPA key, and is waiting to complete the connect.
- Wireless connection has been lost due to interference and/or weak signal, and is waiting to reconnect.
You may not easily know about this kind of problem if Windows isn't configured to notify you. Checking "Notify me when this connection has limited or no connectivity" is recommended.
To establish working connectivity, you can:
- Wait until Windows re-establishes the connection automatically.
- Click the Repair button to try to fix the connection more quickly.
- Find and correct the cause of the problem (e.g., wrong WEP or WPA key, DHCP failure, insufficient signal).
Slow wireless speed
- So you've got a new 54 Mbps wireless network; you've measured actual speed of data transfer; and it's nowhere near 54 Mbps, even with a strong signal? You've just learned the 1st Rule of Wireless Networking: "It never goes as fast as they say it does." The reason is that wireless data can only flow on one wireless link in one direction at any one time, which means that the maximum data transfer rate will be well below half of the raw wireless network speed.
- The raw speed reported by your wireless adapter may not be meaningful -- see Wi-Fi Speed.
- All that said, you may be suffering from weak signal and/or interference.
Too much wireless (RF) interference
- Switch to a different channel
- First try minimally interfering channels: 1, 6, and 11
- If that doesn't solve the problem, try other channels
- Remove interference (e.g., replace 2.4 GHz cordless phone with 900 MHz or 5 GHz cordless phone)
- Use a directional antenna or reflector pointed
- toward desired radio, and
- away from source of interference
- Switch to 802.11a (5 GHz)
Can't connect to the Internet
Can't connect to wireless router or access point
First check May not actually be Connected
- Most such wireless host devices have a web page that can be accessed with a standard web browser (e.g., Internet Explorer). Check the user manual for the address of the web page, and try to connect with a web browser.
- If that doesn't work, try to ping the wireless host; under Microsoft Windows, click Start → Run,
type "%COMSPEC% /k ping WIRELESSHOSTADDRESS" and press [Enter].
- If that doesn't work, check network addresses with Start → Run,
type "%COMSPEC% /k ipconfig /all" and press [Enter].
- The wireless adapter network address will normally begin with the same three number groups as the wireless host web page; e.g., if the wireless host web page is 192.168.1.254, then the wireless adapter should be something like 192.168.1.11.
- If you have a wireless router (not an access point), the Default Gateway should normally be the same network address as the wireless host web page.
- If the wireless adapter network address begins with 169.254... then automatic address assignment has failed, and Windows has assigned a private address that won't work! For troubleshooting you'll probably need to manually configure the network address.
- If all else fails, you may need to reset the wireless host to factory default settings, and start over. Check the user manual for how to do this.
- For more detailed help with Windows XP, see How to troubleshoot TCP/IP connectivity with Windows XP.
Internet isn't working
|To Do:||Please contribute if you can, or check back later for content.|
DHCP isn't working
- Windows: To troubleshoot the problem, try the FixDHCP script.
Getting Windows Remote Desktop to work
- See "Use Remote Desktop for Computers Behind Routers" in Answering Some Common Windows XP Home Networking Questions
Accidentally connecting to neighbor's Wi-Fi
|Tip:||Products with the same (default) SSID seem like a single network!|
See SSID Conflict
- Set a unique SSID in your wireless router or access point.
- Set up security (WEP, or better yet WPA), a very good idea in any event.
Works with no security, but won't work with WEP
|Tip:||WEP can be easily cracked! If possible, use WPA instead. See Wi-Fi Security.|
Wake On LAN (WOL) won't work from the Internet
- For information on Wake On LAN, see:
- The problem is that for a router to send magic WOL packets to your network, you need either:
- an external router interface for generating and sending magic WOL packets, or
- manual enabling of a static route or directed broadcast. Many (most?) low-end routers don't have that capability because of the risk of smurf denial of service attacks.
- Wireless routers with explicit Wake-on-LAN capability
- Software to generate magic WOL packets
Wireless router locks up and has to be restarted
- Possible causes:
- Firmware bug
- Upgrade firmware to the latest version, downloaded from the manufacturer website.
- In some cases it may be necessary to ask Support for more current "beta" firmware.
- Upgrade to a better/newer router
- ARP cache/table overflow (typically in an older router)
- See Firmware bug above
- Overwhelmed by peer-to-peer (P2P) filesharing application (e.g., BitTorrent/Azureus, eDonkey/eMule)
- Reduce the maximum number of connections in the P2P application. Start pretty low and then work up to a maximum safe level.
|Tip:||Much filesharing is unlawful, and risks serious fines.|
If the following error occurs when attempting to run IPCONFIG:
Windows IP Configuration An internal error occurred: A device attached to the system is not functioning. Please contact Microsoft Product Support Services for further help. Additional information: Unknown media status code.
The likely cause of the problem is a wired network adapter that isn't connected. IPCONFIG reports an error because of unknown media status from the wired network device driver.
This issue is known to affect at least some Intel wired network adapters with Windows XP drivers dated 2006 and later. For example, disconnected Intel PRO/1000 MT Mobile wired network adapter in a ThinkPad T41 with driver e1000325.sys:
Version Date Source Status IPCONFIG 126.96.36.199 06/13/2003 Original Windows XP driver Cable Unplugged OK 188.8.131.52 10/26/2004 Lenovo Software Installer Cable Unplugged OK 184.108.40.206 04/27/2006 Microsoft/Windows Update Auto Disable Fails 220.127.116.11 10/24/2006 Lenovo Driver Download Auto Disable Fails 18.104.22.168 03/25/2007 Microsoft/Windows Update Cable Unplugged Fails
Apparently this problem was introduced by Intel in Version 8 of its Windows XP drivers, possibly as an Law of Unintended Consequences of power management-related changes.
Note: Windows Vista does not seem to exhibit this problem with version 8 drivers. [Please confirm!]
- Use Windows XP Driver Roll Back or Uninstall/reboot/reinstall to go back to the original Windows XP driver, or otherwise install an older driver that doesn't exhibit this problem (e.g., Intel Version 7 rather than Version 8).
- Hide any updated driver in Microsoft/Windows Update to prevent unintentionally recreating this problem in the future. Likewise avoid recent driver updates from hardware vendors.
- Click Start → Control Panel → Network Connections, and for any wired network adapters that are Disabled:
- Right-click on My Computer, and click Manage to start Device Manager
- Disable wired Network Adapters that are disabled in Network Connections
- Run IPCONFIG as desired
- Re-Enable wired network adapters in Device Manager
- Click Start → Control Panel → Administrative Tools
- Double-click Services
- Scroll down to Routing and Remote Access
- If Routing and Remote Access is Disabled, change it to Manual
- Start Routing and Remote Access, or Stop and Re-Start it if it's already running
- (Not verified, applies to ThinkPads, possibly other computers)
- Uninstall Access Connections, Keyboard Customizer, Wi-Fi drivers, and Ethernet drivers
- Reinstall in this order Ethernet, Wi-Fi, Keyboard Customizer, Access Connections
- Turning off Power Management and/or changing Advanced options doesn't help.
- The problem occurs whether or not the Intel PROSet for Windows Device Manager is installed.