How To Fix Your Network
Troubleshooting networking and Internet-related problems can be tricky and time-consuming, especially if your ISP is prone to network outages. Read on for some quick networking fixes.
If you can't find your shared PCs or devices on your local network: There are several reasons why you might not be able to see a certain PC on your network, but checking your firewall, your sharing, and your workgroup settings should be a good place to start. For more details, check out "How to Troubleshoot Your Home Network."
Networks with Macs and PCs, or PCs running different versions of Windows (or Linux builds), have their own difficulties--features such as Windows 7's HomeGroups, for example, make networking much easier among Windows 7 PCs but are not quite as easy for other OSs to play along with.
If you can't update all your PCs to run the same version of Windows, read "Set Up Your Home Network: Windows 7 Edition" to see how you can get Windows 7 to play nicely with your network.
If none of your PCs can access the Internet: Turn off your modem and router, and then turn them back on. If that doesn't work, try plugging your PC directly into the modem via ethernet.
If it doesn't work, either, you may have a router problem. If not, your connection is down, and you probably need to call your ISP's tech support line.
If only some of the computers on your network can access the Internet: You're dealing with an issue on your network, and the connection to your ISP is working fine.
First, open the command line (Start Menu, Accessories, Run, then type in cmd); type in ipconfig /renew. This will tell your PC to get a new IP address, a step that can clear up several network issues.
If that doesn't work, try checking the networking settings on each of your PCs by going to Control Panel, Network and Sharing Center, Change Adapter Settings and opening up the panel for the networking device (Local Area Connection for wired networks, or Wireless Network Connection for Wi-Fi, usually) that you're trying to use, and click Details.
From here, you should find clues to what might be going on.
If it says "No" under "DHCP Enabled," then your PC is trying to use a preexisting IP address, subnet mask, and DNS server information to connect to your network.
Normally, most home networks use DHCP (Dynamic Host Configuration Protocol) to automatically assign addresses to new PCs on the network, so all you have to do is plug in (or connect via Wi-Fi), and you're good to go.
Close the Details window and click Properties; click Internet Protocol Version 4 (TCP/IPv4), then Properties. From here, just switch the radio buttons from "Use the following IP address" and "Use the following DNS server addresses" to "Obtain an IP address automatically" and "Obtain DNS server address automatically."
If your IPv4 address starts with "169.254.", your PC is trying to use DHCP to get an IP address and Domain Name Server information for that network automatically.
However, an IP address starting with those two numbers means either that the DHCP server on the network (typically the router, in small home networks) isn't working, or that it's not enabled, and you'll need to manually enter the IP address, subnet mask, and DNS server information on your own.
You can do this by going into the Network Connections window, right-clicking on the network interface you're trying to use, and selecting Properties.
From here, you should select Internet Protocol Version 4 (TCP/IPv4); click Properties, and then both the Use the following IP address radio button and the Use the following DNS server addresses radio button to enter them in.
However, you'll probably need to get that information from whoever set up your home network; most home networks use DHCP to cut down the hassle.