Over the last few months, a lot of my clients have updated their Macs to OS X Lion and most of them love the new OS. However, for some odd reason, a decent number of upgrades to Lion resulted in a very slow Internet connection that was previously very fast.

It doesn’t seem to matter if it’s a MacBook Pro, MacBook Air, iMac, etc, the upgrade to Lion can really slow down Internet browsing speed for some users. And by speed, it’s literally the download speed declining significantly. For example, one user was getting 35 Mbps before upgrading to Lion and suddenly it dropped to 15 Mbps afterwards. This was true in Safari, Chrome and Firefox, so it wasn’t a browser issue either.

In this article, I’ll try to list out the different possible solutions that I’ve used over the last few months and hopefully it helps someone fix their slow Internet problem.

Method 1 – Reset PRAM and NVRAM

Doing this will reset the memory on Mac computers and for some reason has fixed the issue several times. You can reset the PRAM and NVRAM by following these instructions:

1. Turn off your computer

2. Turn on your computer and before the grey screen appears, you need to press the following four keys simultaneously: Command – Option – P – R

3. Keep holding down the keys until the computer restarts and it plays the startup sound for a second time

4. You can now release the keys

You can read more information about this on the Apple site: http://support.apple.com/kb/ht1379.

Method 2 – Turn Off/Reset Cycle

Some users have had success with the following procedure:

1. Remove your wireless network by going to System Preferences, then clicking on Network and then clicking on Advanced. You’ll see the screen below. Click on the wireless network and then click the minus (-) button.

wireless network

2. Now turn off the WiFi completely on your Mac computer. Just click on the wireless icon at the top menu bar and choose Turn Wi-Fi Off.

turn wifi off

3. Now go ahead and perform the PRAM reset mentioned above and also a SMC reset (http://support.apple.com/kb/HT3964).

4. Now go to your wireless router and make sure to update the firmware to the latest version. Unplug it and wait 30 seconds, then plug it back in. Now reboot your Mac computer, turn on the WiFi, reconnect to the wireless network and check your speed!

Hopefully, you are able to get your normal download speed again after doing this.

Method 3 – Airport Express

If you’re using an Airport Express, you may have to use a newer generation Airport Express with the latest firmware. Lots of people have had this problem when using an older Airport Express, so that could also be the culprit.

Method 4 – Multiple Routers

Another issue that can crop up and may not necessarily be related to Lion is if you have multiple wireless routers in your home. If you have several routers broadcasting on the 2.4GHz or 5GHz channels, then you could see some strange interference that causes Internet speeds to slow dramatically.

What you can do here is to turn off all wireless routers except one and see if that makes any difference in the speed. Make sure to reboot the router that is on. If the speed comes back to normal, then you know it’s an issue with the routers being on at the same time. If you have a wireless N router and a wireless a/b/g router, you can try to disable the 2.4 GHz network on the N router and see if that clears things up.

You can also play around with changing the channel on your wireless access point and seeing if that makes a difference.

Method 5 – DNS Issues

Even though it seems to make no sense, changing the DNS servers on your Mac to Google public DNS servers seem to fix the slowness on a lot of people’s computers. Before you do that, though, you can try to flush the DNS on your computer by going to Terminal and typing in the following command:

dscacheutil -flushcache

If that don’t work, go to System Preferences, Network, then choose the appropriate network on the left (Wireless or Ethernet) and click on Advanced. Then click on the DNS tab and remove what’s currently listed there. Or if it’s greyed out, just press the + button and it will overwrite what’s there.

Now type in the following IP addresses:

dns servers

No one has an idea why this works since it really should not matter, but for some folks it really makes a big difference in speed.

Method 6 – Turn Off Firewall

Go to System Preferences, Security and Privacy and click on the Firewall tab. Now Stop the firewall and restart the computer. Go ahead and test the speed on a wired and wireless connection and see what you get. A few people have reported success.

Method 7 – Turn Off IP Flood Detection

With Lion, the way packets and data is sent over the network seems to be different than what it was before. If you log into your router and go the Firewall or Security section, see if you can find an option called IP Flood Detection and turn it off or uncheck it if it is checked.

Method 8 – Turn Off iCloud Features (Photostream)

Some people have mentioned that certain iCloud features eat up bandwidth with certain configurations. Try going to System Preferences, then iCloud and turning off some features like Photostream and see if that makes any difference. You can also try signing out of iCloud and then check the speed.


That’s all I could do up to now, so if you have run across another solution to fix this problem, feel free to post it here in the comments! If you’re still having issues, give us your specs and what you’ve done so far and we’ll see if we can help!