How to solve problems with Wi-Fi in OS X

After some time after the update on OS X Yosemite, many began to face various problems with WiFi, ranging from loss of connectivity and ending with the inability to connect to long-known networks.

The reasons for the appearance of these problems are different and you can only exclude them all by pure installation of OS X. If for some reason you do not want to do a clean installation, we have several ways that all problems with WiFi should be solved.

Delete the files responsible for setting up the network

Manually deleting the files responsible for the network will cause the computer to create new files that are likely to be free of existing problems. Here’s what you need to do:

1. Disable WiFi.
2. Open the Finder, hold Command + Shift + G and paste in the appeared window the path:
   / Library / Preferences / SystemConfiguration /
   
3. Locate the following files in the folder and move them to the backup folder (just in case) on the desktop.
   com.apple.airport.preferences.plist
com.apple.network.identification.plist
com.apple.wifi.message-tracer.plist
NetworkInterfaces.plist
preferences.plist
4.  Restart the Mac.
5. Turn on WiFi.

This operation will cause the Mac to create deleted files from scratch. If this does not solve your WiFi problems, go to the next method.

Create a new WiFi network with a cast MTU

Now we will change the basic settings for WiFi. We manually change the MTU size – the maximum size of one data block.

1. Open System Preferences and select Network.
2. Click on the “Placement” box and select “Edit Placements”.
   
3. Click on the plus and add a new placement with any name.
4. Now go to the “Advanced” tab and go to the “Hardware” section.
5. Set the configuration “Manual” and set the MTU packet size to 1453.
   

Apply the changed settings and reload the applications that need Internet access. Setting the size of MTU 1453 is an old admin trick, which has long solved some problems with connecting to the network.

Bonus

Here are some less difficult and effective tips that can also help:

1. Connect to 2.4 GHZ networks.
2. Set the channel of 5 GHZ routers between 50 and 120.
3. Turn off Bluetooth. In some cases, this solves the problem with WiFi.

If none of the above methods work, try reinstalling OS X from scratch. Even if you did not want to do this, it’s better to spend some time on installation than working with a computer without WiFi.