Macs, like any computer, are vulnerable to losing their Wi-Fi connections. If you have reset your router, found that other devices are connecting to it, and your Mac is still refusing to go online, then it’s pretty certain that the issue stems from the Mac itself. This article will cover adjusting packet size, resetting the PRAM and SMC, reconfiguring the DNS, changing location, and deleting and re-adding the WiFi configuration.
Diagnose Wi-Fi Connection Problems
A good place to start when looking at Wi-Fi problems on your Mac is to diagnose exactly what the issue is. macOS has a Wi-Fi diagnostic tool built into it that can help.
To open the macOS diagnostics tool, hold the Option key then click the Wi-Fi icon at the top right corner of the desktop, then click “Open Wireless Diagnostics”. You can follow the wizard here for some basic pointers, but the really useful function is the Performance Graph, which you access by click Window at the top of your screen then Performance.
This will open a graph showing the transmission rate, signal quality and noise level on your Wi-Fi network.
Transmission rate and signal quality tend to be connected. The worse the signal, the worse the transmission rate. You can improve your signal by making sure that your Mac is positioned closer to your router.
If your noise levels are high or spiking, you can try finding a better Wi-Fi channel or logging into your router settings through your browser and changing from the 2.4GHz to the 5GHz band.
Wi-Fi Switching Off After Sleep Wake
This one’s a common problem for Mac users, where the Wi-Fi disconnects when the Mac wakes from sleep. Here’s a possible solution:
Go to the “Apple menu -> System Preferences -> Network”. In the left-hand pane, click Wi-Fi, then “Advanced” in the bottom right corner.
On the next screen, select every network in the list using Command + A, and use the “-” icon to remove them all.
Back in the main Network window, click the Locations dropdown, then the “+” icon and give the new location a name of your choice. Click Done to use this location from now on.
Finally, reconnect to your home Wi-Fi network. With a bit of luck, it should stop disconnecting upon Sleep Wake from now on.
Disconnect USB and Wireless Signal Devices
Before moving onto the nitty-gritty methods of fixing your Mac’s Wi-Fi woes, there’s something simple you can try that might just solve everything. Quite a lot of Mac users have reported that disconnecting certain USB 3 and USB-C devices has solved their problems. So the first thing to try is disconnect your USB devices one by one and see if the Wi-Fi comes back.
Why does this happen? Certain USB devices emit wireless signals that can interfere with the Wi-Fi, while devices like USB hubs have been known to outright disable the Wi-Fi port (sort of like how plugging in an ethernet cable automatically disables Wi-Fi).
So unplug all your devices, then observe whether your Wi-Fi returns after removing a particular one.
Reset the NVRAM/PRAM and SMC
I first started having connection issues while running macOS Sierra’s public beta. Of course, start by restarting your Mac to see if this resolves the issues. Otherwise, try to reset the PRAM (Parameter Random-Access-Memory) / NVRAM (Non-Volatile Random-Access-Memory) and the SMC (System Management Controller). These are the portions of your Mac that control basic operations critical for basic system function.
1. Press and hold the power button on your Mac to completely shut it off. Hard discs and fans need to stop spinning, and the screen needs to go dark.
2. Power on your Mac.
3. Immediately after you hear the startup sound, press and hold the Command + Option + P + R keys.
4. Keep holding them down until you hear the start up sound again and see the Apple logo.
5. Release the keys, and the PRAM/NVRAM will have been reset.
This process will vary heavily depending on whether or not your Mac is a desktop or laptop and if it has a removable battery or not. Apple covers this process quite heavily.
The following attempts at getting back online will all require you to begin with your Mac’s “Network Settings.” To get there:
1. Click on “System Preferences” from the dock, or click it from the top-left Apple logo’s drop-down menu.
2. Click “Network” from the newly-opened window.
Reconfigure the DNS
DNS stands for Domain Name Server, which essentially changes web addresses that we are able to read (e.g. www.google.com) to IP addresses that the server can understand. This acts as a “phone book” of sorts for the Internet. Sometimes your service provider’s given DNS will not work properly, in which case we can use safe and free publicly available DNS options like Google’s.
1. Click “Advanced.”
2. Select “DNS” from the network settings.
3. Click the “+” icon.
126.96.36.199 into the box and press Enter (these are Google’s DNS options).
5. Click “Okay.”
Now try to surf the Web.
Adjust Packet Size
Are some pages loading just fine and others failing completely? This could have to do with the amount of packets that are able to be transmitted. In layman’s terms, this is the amount of data able to be transmitted over the network. We can adjust the value so that certain sites are able to load.
1. Click “Advanced.”
2. Start by selecting “Hardware” in network settings.
3. Change the “Configure” setting from “Automatic” to “Manually.”
4. Change MTU from “Standard (1500)” to “Custom.”
5. Add the value “1453” into the box and press Enter. Click “Okay.”
Try surfing the Web a bit to see if this was able to solve the issue.
Change Location and Renew DHCP Lease
Sometimes the automatic location determined by your Mac will not get settings 100% correct, in which case we can set up a custom location and settings that go along with it. This is where we can also renew a DHCP lease and IP address. DHCP is a protocol for arranging IP addresses, and changing that can make sure traffic is being directed accordingly. Now after all of that tech jargon, here is how to do it.
1. Again in network settings, click “Edit locations” from the drop-down menu where “Automatic” is currently selected.
2. Click the “+” icon and name this new “location.” You can name it literally anything you would like; the name itself does not affect anything. Press Enter and click “Done.”
You will now notice that “no IP address” appears under WiFi on the left menu bar.
3. Click “Advanced,” then “TCP/IP” from the menu bar.
4. Click “Renew DHCP Lease.” A new IP address will be assigned.
5. Click “Okay” and try to surf the Web.
This article was updated in December 2019.