Fix OS X Mountain Lion Wireless Connection Problems
OS X Mountain Lion has been a painless upgrade for most users, but there are a fair amount of people experiencing some unusual wireless connectivity problems and issues. Mainly, the wi-fi connection seems to drop at random, or the Mac simply won’t stay connected to a wireless network for long. Sometimes it automatically reconnects and sometimes it doesn’t.
If you’re experiencing these wifi issues you’re not alone, the good news is that we have a few solutions that appear to resolve the connection problems in Mountain Lion. For best results, try combining both of these tips.
Fix #1: Add a New Network Location & Renew DHCP
This may work best for those who upgraded from a previous version of OS X to Mountain Lion but if you’re having the wifi drop issue go ahead and do it anyway because it is consistently successful with addressing wireless issues:
- Open System Preferences from the Apple menu and choose “Network”
- Pull down the “Location” menu and choose “Edit Locations…”
- Click the [+] button to add a new location, name it whatever you want then click Done
- Back at the “Network” screen, click the “Network Name” menu and join the wireless network
Your wireless connection may now be active and working fine, but renew the DHCP lease anyway:
- From the Network panel, click on the “Advanced” button in the lower right corner, then click the “TCP/IP” tab
- Make sure “Configure IPv4:” is set to “Using DHCP” and then click the “Renew DHCP Lease” button, click “Apply” when prompted
- The appropriate DHCP settings should be renewed from the connected router, click “OK” and exit out of System Prefs
The network location and DHCP renewal tip resolved similar wifi problems in Lion, and it seems to work in Mountain Lion too for many users.
Fix #2: Change MTU Size to Prevent Dropped Connections
This is a bit geeky but bare with us: MTU stands for Maximum Transmission Unit and controls the largest packet size allowed for transmission over the network. If this setting is greater than network capacity, the computer will experience packet loss and dropped connections. The default setting of 1500 is somewhat aggressive and some networks reject packets of that size, but it turns out that 1453 is just small enough to maintain a consistent connection with most networks but just large enough to not cause any slowdowns, it’s the magic number and an old cisco networking secret.
- Open System Preferences from the Apple menu and select “Network”
- Click the “Advanced” button in the lower corner, followed by the “Hardware” tab
- Pull down the “Configure” menu and set to “Manually”
- Change “MTU” to “Custom” and set the field to “1453”
- Click “OK” and close out of Network preferences
Be sure you’re joined on a wireless network, close out of System Preferences, and enjoy the internet as usual.
Additional Troubleshooting Tips
Sometimes just rebooting the Mac is sufficient to resolve the problems, but that’s not always the case.
Also, some wireless network problems are due to interference with other networks, be sure to check the channel of the router you are connecting to and make sure the connection strength is strong. Now is probably as good of time as any to fire up the all new Wi-Fi scanner in Mountain Lion and check out your network health.
In some situations, performing a clean install of Mountain Lion has worked for users who have consistently upgraded from ancient versions of OS X onward, but realistically that should be considered a worst case scenario and for most users you can get the same effect simply by adding a new Network Location as instructed in fix #1 above.
Let us know in the comments if these tips work for you, or if you find something else that works too.
Thanks to everyone who wrote us about this topic