Click “OK” and close out of Network preferencesīe sure you’re joined on a wireless network, close out of System Preferences, and enjoy the internet as usual.Change “MTU” to “Custom” and set the field to “1453”.Pull down the “Configure” menu and set to “Manually”.Click the “Advanced” button in the lower corner, followed by the “Hardware” tab.Open System Preferences from the  Apple menu and select “Network”.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. If this setting is greater than network capacity, the computer will experience packet loss and 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. Fix #2: Change MTU Size to Prevent Dropped Connections 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. The appropriate DHCP settings should be renewed from the connected router, click “OK” and exit out of System Prefs.Make sure “Configure IPv4:” is set to “Using DHCP” and then click the “Renew DHCP Lease” button, click “Apply” when prompted.From the Network panel, click on the “Advanced” button in the lower right corner, then click the “TCP/IP” tab.Your wireless connection may now be active and working fine, but renew the DHCP lease anyway: Back at the “Network” screen, click the “Network Name” menu and join the wireless network.

Click the button to add a new location, name it whatever you want then click Done.

Pull down the “Location” menu and choose “Edit Locations…”.

Open System Preferences from the  Apple menu and choose “Network”.

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:

Fix #1: Add a New Network Location & Renew DHCP

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