One of Apple’s focuses with the recent 10.10.2 update was for Wi-Fi reliability; however, given that in doing so Apple adjusted the code for its Wi-Fi services, some systems that had stable Wi-Fi connections before the update might now experience problems. In addition, as with any update, sometimes those with ongoing problems may see them persist. If you are experiencing Wi-Fi problems after updating to OS X 10.10.2, then there are some things you can try to stabilize your connection.
General “blind” approaches
These routines are general and non-specific approaches for addressing many problems in OS X, where they may or may not help, but they can’t hurt to try. They also will address problems without changing too many settings:
- Reset hardware settings on your system, including the PRAM (see here) and System Management Controller (see here).
- Restart in to Safe Mode (hold Shift at startup), and then restart normally again.
- Run a permissions fix on the boot drive using Disk Utility.
- Disable any security software, including the OS X firewall in the Security system preferences.
- Restart your router, and update its firmware, if applicable.
OS X supports separate network configurations in profiles called Locations, so you can use this to create a new Location to bypass some possible configuration errors with the current one. To do this, open the Network system preferences where you will see a Location menu at the top of the preferences pane. In this menu, select Edit Locations and then click the plus button in the drop-down panel to create a new location. Call it whatever you want, and it will be populated with the system’s default hardware network ports (Ethernet, Wi-Fi, FireWire, etc.). Click the Wi-Fi port, and ensure it is on and connected to your preferred Wi-Fi network. Then click Apply to save your changes.
Another setting you can try adjusting is your Wi-Fi’s Maximum Transmission Unit size. Networks send data in small separate packets, and this is the maximum size that will be sent for each packet. If for some reason your router and other network hardware is not accepting the default packet size of 1500 bytes, then trying another smaller value may help. To do this, select the Wi-Fi port, then click the Advanced button. In here, go to the Hardware tab and select Manually from the Configure menu. Then select Custom from the MTU menu, and try one of the following packet sizes: 1456, 1453, 1492.
For each of these sizes, click OK and try accessing network services and the Internet to see if your Wi-Fi connection is more stable. Note that by reducing the packet size with a smaller MTU setting, you will increase your network overhead (network throughput used for headers and other non-data communication); however, unless you need maximum performance for computer-to-computer communication on your local network, then a difference of under 50 bytes for the MTU setting will not be notable, especially if it stabilizes the connection.
Rebuild your Mac’s entire network configuration
While changing your network location will apply new settings to your Mac’s network configuration, it still uses the same configuration files and does not replace them. To fully reset your network configuration, go to the Macintosh HD > Library > Preferences > SystemConfiguration folder, and then remove the following files. Note that when doing so you may have to authenticate to delete these files or move them out of the SystemConfiguration folder, and when done you will need to re-visit the Network system preferences to set up your locations and Wi-Fi settings again, but hopefully this wil clear your problems.