If your web browser, your email program or any of a hundred other internet-connected apps on your Mac start complaining about not having a connection, you may have to do a bit of sleuthing to figure out the source. After all, a disruption anywhere along the chain between your Mac and a distant server could cause an outage, and the right place to look isn’t always obvious. We suggest trying each of the following steps, in order, until you’re able to connect again. BY JOE KISSELL.
Try another site or app
To make sure that the problem isn’t restricted to one website, try visiting another – preferably one that’s highly reliable, such as Google’s homepage.
Similarly, to establish that the issue isn’t limited to the current application (such as your email program or web browser), try connecting to the internet with another app. If only one site seems to be having problems, visit Down For Everyone Or Just Me (isup.me) and enter the problematic site’s URL. The service will tell you whether computers elsewhere on the internet can successfully connect to the site. If they can’t, at least you aren’t alone – though you’re out of luck for now.
Use Network Diagnostics
Certain types of network problems may cause your browser to display a Network Diagnostics button. This behaviour is OS X’s way of offering to help debug your connection problem, and we suggest that you accept the help. (If you don’t see a button, you can launch Network Diagnostics manually: Choose Apple menu > System Preferences and click Network. Click Assist me, and then click Diagnostics.)
The Network Diagnostics utility will guide you through a series of procedures and tests on subjects that range from Ethernet and Wi-Fi connections to network configuration and DNS servers. The utility steps you through the process for one network configuration, or location, at a time. Sometimes the utility can repair problems itself, but when it can’t, it usually provides more detailed information about the nature of the problem and suggests ways of solving it.
If your Mac connects to the internet through Wi-Fi, check the Wi-Fi menu (at the top right of the screen) to confirm that your system is connected to the intended network. Macs have been known to hop onto less desirable networks at inconvenient times.
If the menu’s icon has an exclamation point superimposed on it (indicating that it can’t successfully connect to any network), try choosing Turn Wi- Fi Off from the menu, waiting about 30 seconds and then choosing Turn Wi-Fi On. If that tactic doesn’t work, restart your Mac. Sometimes that simple-yet-seemingly-purposeless action turns out to be the only way to clear certain wacky errors that prevent Wi-Fi from connecting.
Try another device
If you have access to another computer or mobile device that uses the same internet connection that your balking system does, check to see if you can connect to a website on that device. If not, you can rule out your Mac as the source of the problem and look elsewhere for a solution.
On the other hand, if the second device can connect to the internet and your Mac can’t, even after you restart it, skip ahead to the step ‘Check your DNS settings.’
Reset your router
For network problems that lie outside your Mac, if you own or control the network device that your Mac connects to
(such as an AirPort base station, Time Capsule, router, switch or hub), turn that device off, wait for about 10 seconds and then turn it back on. Wait for the network device to power on completely (in some cases, this may be a multistep process that takes several minutes), then try connecting again.
If more than one such device is situated between your Mac and the internet – if, for example, you have an AirPort Express connected to a cable modem – start with the device closest to the internet and work your way back toward your Mac, cycling the power on each device as you go.
Check your DNS settings
The Domain Name System enables your machine to convert domain names (like apple.com) into IP addresses (such as 184.108.40.206) that computers can understand. If the DNS server that your Mac uses is offline, slow or faulty, you may be unable to connect to any site or service by name.
If none of the websites you try – including very stable ones such as Google – respond, here’s an easy way to check whether DNS is functional. In your browser, type this URL: http://220.127.116.11. That address should bring up the Google website. If it does, your internet connection is fine, and the problem involves your system’s ability to look up domain names.
To fix that problem, open the Network pane of System Preferences and select your network connection in the list that appears on the left. Click Advanced, and then click DNS. Look in the DNS Servers field, and you should see one or more IP addresses listed there. If those addresses are enabled (a status that OS X indicates by showing them in black type, rather than grey), select each one in turn and click the minus (-) button.
Then, regardless of whether you already see IP addresses on the list in grey, click the plus (+) button and enter 18.104.22.168; afterward, repeat the process with 22.214.171.124. (These two addresses point to OpenDNS, a free DNS service that may be more reliable than the default servers that your ISP uses.) Click OK and then click Apply. Now cross your fingers and try connecting again.
Getting back online
Even if you follow all of the steps outlined in this section, you may not connect to the internet successfully, because some outages are beyond your control. Because of the internet’s distributed nature, an equipment failure at an ISP can affect users besides its own customers. And on a larger scale, accidental damage to a major fibre-optic cable can wipe out internet access to a large region.
With some internet outages, all you can do is wait them out. But if the problem lies beyond your local network, your ISP should at least be able to tell you the nature of the problem and provide an expected repair time.
by Joe Kissell