One of the more perplexing and annoying wi-fi problems is having a strong wireless signal but still no Internet connection. Unlike issues like not having a wireless connection or dropped wireless signals, when you have a strong wireless signal, all indicators seem to be saying everything's OK -- and yet you can't connect to the Internet or, sometimes, other computers on your network.
Wireless Troubleshooting: Wireless Signal but No Internet Connection
Here's what to do about this common problem:
1. Check the wireless router
If the issue occurs on your home network, log in to the wireless router's administration page (directions will be in your manual; most router's admin sites are something like http://192.168.2.1). From the main page or in a separate "network status" section, check if your Internet connection is actually up. You can also go to the router itself and look at the status indicator lights -- there should be a blinking or steady light for the Internet connection. If your Internet connection is down, uplug the modem and the router, wait a few minutes, and plug them back in. If this doesn't refresh your service, contact your Internet Service Provider (ISP) for assistance, since the problem is likely on their end.
2. Open your browser
If you're using a wi-fi hotspot (at a hotel, cafe, or airport, for example), you may think you can check your email (e.g., in Outlook) once you have a wireless connection signal. Most hotspots, however, require you to first open a browser and view their landing page where you'll have to agree to their terms and conditions before using the service (some will also require you to pay for the access). This holds true whether you're using a laptop or a smartphone or other portable device to access a public wireless network.
3. Re-input the WEP/WPA Code
Some operating systems (like Windows XP) won't warn you if you put in the wrong wireless security code. Although your laptop may show you have a strong wireless signal, if the wrong key is input, the router will refuse to properly communicate with your device. Re-input the security key (you can right-click on the icon in the status bar and click Disconnect, then try again). If you're at a public wi-fi hotspot, make sure you have the correct security code from the hotspot provider.
4. Check the MAC address filtering
A simiilar problem is if the router or access point has MAC address filtering set up. MAC addresses (or Media Access Control numbers) identify individual networking hardware. Routers and access points can be set up to allow only certain MAC addresses -- i.e., unique devices -- to authenticate with them. If the network you're connecting to has this filtering set up (e.g., on a corporate or small business network), you'll need to have the MAC address of your computer/device's network adapter added to the permission list.
5. Try a different DNS server
Changing your DNS servers, which translate domain names into actual web server addresses, from your ISP's to a dedicated DNS service -- such as OpenDNS -- can add more connection reliability and also speed up your Internet access. Enter the DNS addresses manually in your router's configuration pages.
These are the most common fixes for wireless problems. Another source that can help you diagnose and solve wireless issues on your laptop is this pretty technical Laptop Internet Connectivity flowchart from the Laptop Repair Workbook.
(Note: This article is also available in a PDF version for saving to your computer for reference before going on the road. If you need further help or want to discuss wi-fi or other mobile computing topics, feel free to visit our forum.)