When things go awry, especially with Wi-Fi networks, it can be frustrating trying to track down the culprit. Before you start moving appliances and drilling holes into your walls, why not take look at our common issues with networks and how to correct them so you can get back to watching Netflix in the bathroom.
Q. When my MacBook is right next to the wireless router, it connects, but if I move to another room, it then asks for the password, even though other computers can connect just fine.
AirPort wireless cards in Macs aren’t immune to hardware failure—yet!
A. This is a hardware fault with your MacBook’s AirPort card or the antenna. The AirPort icon still reports a good signal because it is measuring the signal received from the router and the problem doesn’t affect the receiver. But the transmitter’s signal isn’t strong enough to reach the router unless the range is virtually zero. It’s time to get the AirPort card replaced—you can do so at an authorized Mac service center.
Q. My iMac used to be able to create computer-to-computer networks with my Windows laptop. Since upgrading to Snow Leopard, I can’t do this. Why?
A. If you use the Mac as a Wi-Fi base station, then Windows PCs won’t be able to connect to your network unless you untick the Require Password box. Alternatively, use a separate wireless router and connect both computers to that.
Q. How can I configure my AirPort Extreme to run both the 2.4GHz and 5GHz bands simultaneously as two independent networks?
A. It already uses both frequencies by default. The newer wireless n models automatically pick whichever band offers the best reception. Separate your network traffic at the IP address level, using a router—not by using different radio frequencies.
Q. When I’m using Microsoft Office, I frequently get asked whether I want the application to accept incoming network connections.
A. Incoming connections are network packets that were not specifically solicited by the application. Office applications listen on certain ports to receive notification of updates, for example. If you have your firewall set to block all incoming connections, it won’t be able to do this, and that’s why it pops up the message, asking if you want to let this one through. If you trust the application, it’s safe; probably safer than leaving Office unpatched, in fact.
Q. After reinstalling OS X, my iBook won’t accept the network password, even though all the other computers in the house connect perfectly well…
A. Assuming that you’re definitely using the right password for the router (and not confusing the router admin password with the AirPort password, say) the most likely problem is a corrupted plist, and deleting this file should fix it. You’ll find it in the folder Macintosh HD/Library/Preferences/System Preferences.
Q. I can use video chat with Skype, but iChat has horribly choppy video. How can I fix this?
Video chatting is a lot more complicated than text.
A. iChat uses an external SNATMAP server to tell each party which IP address and port numbers should be used for the chat session. Some routers block this activity because it could be used by hackers. Sometimes you can get around this by unbinding the Session Initiation Protocol (SIP) from the port that iChat uses. Check your router manufacturer’s support pages for the telnet commands to do this.
Q. How can I use my home Mac to access my Windows XP computer at work?
GoToMyPC.com lets you access a PC from any browser. There’s a free 30-day trial.
A. You could use the Remote Desktop Host included with Windows XP Professional, but it’s probably easier to use a web service like GoToMyPC.com, which enables you to access your Mac or PC from anywhere (for a price, starting at $9.95/month). Or try LogMeIn Free (logmein.com), since it works with both Mac and PC—and it’s free.
Q. I use a modem/router supplied by my ISP with Wi-Fi turned off, connected via Ethernet to a Time Capsule in bridge mode. This provides my wireless network. However, I’m restricted by the five-connection limit of my ISP’s modem/router, even though I’m using Time Capsule. How can I get around this?
A. In bridge mode, the AirPort Extreme and Time Capsule don’t provide any network address translation. They just rebroadcast the network packets wirelessly, so you’re still restricted to the five-address limit imposed by your modem/router.
Fortunately, however, the solution isn’t a convoluted one. All you need to do is put Time Capsule into NAT mode, using AirPort Utility. This will take one of the five IP addresses handed out by the Livebox and split it into as many wireless addresses as you need.
Q. I have a PS3 wirelessly connected to my network, but some games require NAT on my router to be “open,” not “strict” or “moderate.” How can I set this up?
Check your game’s manual for the right ports to forward.
A. To open NAT, you need to use the network configuration settings on the PS3 to give it a static IP address that lies outside the range managed by DHCP. For example, if your router has DHCP configured with an address range of 192.168.1.1 to 192.168.1.30, you could give your PS3 a static IP address of 192.168.1.31. Next, enable Universal Plug and Play (UPnP) and finally, forward the right ports for your game.
Q. I have added a Time Capsule by connecting it directly to my broadband modem with an Ethernet cable. But my Mac now frequently selects the wrong network and AirPort Utility can’t see the Time Capsule at all.
Apart from its Wi-Fi abilities, Time Capsule comes with 1TB to 2TB of storage.
A. Instead of connecting to the Wi-Fi network from the modem and reaching the Time Capsule through that, reconfigure the Time Capsule to create its own Wi-Fi network and turn off Wi-Fi on the modem. Having two wireless networks just increases interference.
Q. I recently changed my broadband provider. My networked printer, which used to work perfectly, now causes me to lose my connection every time I turn it on.
A. Your printer probably has a static IP address assigned which now conflicts with the IP address range used for DHCP on the new router. Change the printer to use DHCP as well, or move the static address to an unused number.
Q. I have moved my iTunes and iPhoto libraries to a networked hard drive. Unfortunately, I can no longer use Front Row to watch or listen to my media. Is there anything I can do to point Front Row at an external drive?
A. Front Row won’t access networked drives directly, but you can easily create an alias to one and drop that into your Movies or Music folder. Provided that the network drive is accessible and mounted, Front Row should display this perfectly well, though there might be a short delay for Front Row to buffer the stream before it begins playing.
Q. What is the best way to add really old Macs (G4 and G3 iMacs) to my wireless network?
It’s quite possible to connect an older Mac to your network.
A. Use a wireless bridge. It plugs into the Ethernet port on your Mac and lets the G4 ignore the wireless aspect. The bridge itself will wirelessly relay all the traffic from the G4 to your main router without the Mac ever being the wiser. The AirPort Express will do this, and Belkin and Linksys also have compatible bridges.
Q. What is MAC access control, and will enabling it improve my Wi-Fi security at all?
A. The Media Access Control (or MAC) address is hard-coded into every network device when it’s manufactured, and it’s unique to each one. You’ll find it by selecting About This Mac from the Apple menu and then clicking the More Info button. Then select Network from the list on the left and scroll the right-hand pane all the way down to the bottom, where you should see the MAC address in question presented as six two-digit, hexadecimal numbers.
Q. I sometimes get an error message that says “IP Configuration.” Nothing else seems wrong. Should I worry?
A. That means another device tries to connect with the same IP address as you. You were there first, so the other device is locked out, but OS X warns you about the conflict. Check that your network devices are using DHCP, or static IP addresses that don’t overlap the DHCP range or conflict with each other.
For the first backup, plug your Time Capsule directly into your Mac with an Ethernet cable. Open Time Machine’s Preferences, click Select Disk and then Set Up Time Capsule. This will open the AirPort Utility and your Time Capsule should appear in the left-hand column.
Use the setup wizard to help you with the initial configuration. Choose Connect to a network using Ethernet. The first backup will take a while since it must copy every file. Once it’s done, unplug it from your Mac and connect it with the same cable to your broadband router.
Run AirPort Utility and set Time Capsule to “Create a wireless network.” Right-click the AirPort icon on the menu bar and switch to this network. Reduce interference by disabling Wi-Fi on the router via the webpage at the IP address of your non-Time Capsule router, if you have one.
Open System Preferences > Network and select the network connection you want to troubleshoot. Click Assist Me at the bottom and then click Diagnostics in the dialog. Then click Continue. You’ll see a column of green “lights” labeled Network Status.
The first light (either yellow or red) indicates the most likely source of the problem. For example, if the phone cable to your modem is loose, the AirPort, AirPort Settings, and Network Settings lights will all be green, but the ISP light and those below it will be red.
The diagnostic utility will suggest some solutions itself, but don’t expect too much. If turning the modem and router off and on doesn’t fix things, then it’s all out of ideas. But you can start trying other things, like swapping out cables or checking your phone line microfilter.
