Mac can't connect to Wi-Fi, how to fix?

Mac can't connect to a Wi-Fi network or connection is slow and unstable - how to fix?

Today, Wi-Fi networks are found in most homes where computers and mobile devices are used. Furthermore, free Wi-Fi networks are available in public areas such as cafes, hotels, airports, business buildings, various SPA centers, etc. Wi-Fi connections are used for personal use, but are also well integrated into various other systems, such as security cameras and yard lightning. Since Wi-Fi is widely used, a lost or weak signal can be very frustrating.

Loss of Wi-Fi connectivity might result in problems with work or inaccessible features such as 'smart home', whereby all electronic devices are connected through the network. Even casual activities that include movies, home entertainment, or music can be affected, unless you download everything to internal or external storage. There are three main causes of Wi-Fi network issues: 1) router errors; 2) the Internet Service Provider [ISP] network is down or experiencing issues, and; 3) problems with your device. There can also be issues with macOS software running on your computer. In this article, we describe some Wi-Fi network issues and possible solutions.

 wifi-introduction

Table of Contents:

Check your software compatibility

First, try some easy steps. Some users have reported that the Wi-Fi problem appeared after upgrading their Macs. This particular problem has been widely encountered with Mac OS version El Capitan - once the update process finishes, issues with connecting to wireless networks occurred. Apple released an update for software to address the issue, but MacBook Air owners still reported problems, since for many, a Wi-Fi network was the only available connection to the Internet. iFolks users found an option to access the update: share the connection from their mobile phones. If this option is available to you, it might be worth a try, but bear in mind that cellular data restrictions will have a maximum available GB. Furthermore, Wi-Fi problems are sometimes encountered when computers run a beta version of MacOS. For example, issues with frequent Wi-Fi dropouts while running High Sierra beta (but resolved in the 10.13.12 update).

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Look up, if there are any Apple WI-FI recommendations

Since all modern versions of macOS include many troubleshooting tools, your computer will check for issues while attempting to connect to a Wi-Fi network. The recommendations are displayed in the Wi-Fi status menu, which can be accessed by clicking the Wi-Fi logo in the menu bar at top right of the screen.

wifi-recomendation

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Contact your Internet service provider

Network issues might be the result of problems with your Internet Service Provider (ISP). In this frustrating case, the only option is to contact them or check 'network status' on their website to check if they are encountering issues. Even if their servers are working well, there might be problems with cables. For example, if the network has an issue during bad weather, it might be caused by water on the cables.

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Reboot your Mac

Resetting electronic devices is a good idea, and so this process is similar to the previous one. Turn the Mac off, disconnect the power cable, and wait for 30 seconds. Turn the computer on and check if the problem is solved. Otherwise, disable the Wi-Fi adapter and wait a few seconds before turning it back on - this will force the Mac to re-scan for available networks. To turn off the Wi-Fi, click the Wi-Fi logo in the menu bar at the top right of your screen and choose Turn Wi-Fi off.

restart

Alternatively, try to disable Bluetooth. This might seem confusing, but users report that turning off Bluetooth solved network issues. To disable it, click the Bluetooth icon located next to the Wi-Fi icon and choose Turn Bluetooth off.

disable-bluetooth

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Reboot your router

As we all like that our devices to connect automatically to a home network, routers often experience significant uptime. This can result in crashes, since the demand outweighs its capacity. The solution in this situation is quite simple: disconnect the router from the power adapter and keep it in this state for about 30 seconds. Then, reattach the power cord and turn it back on.

Keep the router cool

Electronic devices and components will not work if they exceed their maximum temperatures. Wi-Fi routers will fail if they are not covered or positioned to prevent excessive temperatures. Manufacturers include various protections against overheating (depending on the device), but most will simply stop working or decrease performance to the minimum.

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Forget and reattach your Wi-Fi network

Removing the existing network, and performing a fresh connection sometimes solves erratic problems related to Wi-Fi network connections. The effect is similar to a router reset, without managing the power source. To forget a Wi-Fi network, open the Mac System Preferences and select Network. In the new window, select your Wi-Fi network from the list on the left and then click Advanced. You will see a list with all saved networks - select the problem network and click the remove (-) button. Confirm your action by clicking Remove in the popped-up window. Once you have removed a network from the preferred list, all Apple devices that use the same Apple ID and iCloud Keychain will not automatically connect to it. The last step is to connect to this particular network manually - select it from the list and enter the password when requested.

forget-wifi

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Check the location of your router

Since Wi-Fi routers are based on electronic waves, the location of the router might be a problem. When you position a router, avoid any large metal surfaces such as radiators or filling cabinets. Another important factor is the distance between the computer and source of electronic waves. Try to position the Mac (or other device) using the Wi-Fi network closer to the router. Check if this solves the issues. Signal strength can be affected for a number of reasons. For example, thick walls concealing significant metal can result in 'dead spots' where the Wi-Fi signal is unreachable. Some third-party applications draw a map of a building's Wi-Fi signals. NetSpot is an example - this is a paid application with a cost of $7.99. These apps require you to move your computer through the building to inspect signal strength. If you find weak spots, you can obtain a Wi-Fi extender device that expands areas of the wireless signal. When you set up these devices, ensure that you change the SSID (Wi-Fi network name) and password to be identical to your router settings - this will allow your Mac to automatically switch between signals when it reaches a spot where the strength differs. Otherwise, you will be asked to type in the password, and the connection will be lost until you confirm the action. Problems are sometimes caused by other electrical devices such as microwaves, fans, wireless phones, or motors. For example, the Wi-Fi connection is lost whenever you use a microwave oven. This is a result of mircowave interference. In this case, move the router away from the microwave device, that could be affecting the signal.

5ghz-wifi-list

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Call Apple's Wireless Diagnostics to locate the problem

Modern versions of macOS include many built-in diagnostic tools, including those relating to Wi-Fi networks. You can launch the Wireless Diagnostics application, which displays three graphs of signal performance. It also checks for possible issues with your network and/or Wi-Fi adapter. To generate performance graphs, launch the tool by using Spotlight or hold down Option and click the Wi-Fi icon in the menu bar at the top right of the screen. Then select Open Wireless Diagnostics. Before you launch the tool by clicking Continue, click on Window in the menu at the top of the screen, and then select Performance. Alternatively, you may use the keyboard shortcut of Option, Command, and 5. This will display three graphs of transmission rate, signal quality, and signal and noise levels. Inspecting these graphs might allow you to identify issues.

performane-graph

The top graph monitors the data rate of your Wi-Fi network in Mbps. Stats are taked from the router and other equipment connected to it. To troubleshoot problems, you must monitor the rate. Any dips, or a complete drop-off, will indicate an issue.

data-rate

The middle graph displays signal-to-noise ratio over time - it should be a straight line, possibly with small spikes. If you notice frequent dips in the line, or a complete drop-off, something is interfering with your Wi-Fi signal. Using this graph, you can locate a problematic device by a process of elimination. For example, turn on a microwave oven and check the graph for possible drops.

quality-graph

The last graph, labelled Signal, displays two lines. The top is signal strength and the bottom measures noise. Both stats are shown as dBm (Decibel to milliwatts), a commonly used unit for quantifying the ratio between two values - in this case signal to noise. A good signal should have a strength of between -60 and -10 dBm and the noise level should be below -75dBm. In other words, the smaller gap between the lines, the worse the Wi-Fi signal. Even the position of the router can affect the strength and noise level. Therefore, try to change both vertical and horizontal positions of the device.

signal-graph

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Check for available competitors to your router

One of the most common issues experienced when there are several Wi-Fi networks within the same building is interference of waves. Separate routers might possibly use the same channel. To find out about used channels and other related information, Wireless Diagnostics can help. The Scan function, which is accessible through the Window menu at top left of the screen displays information about all detectable networks. Even a similar name might cause problems. Routers usually succeed in automatically selecting proper channels, however, if you are experiencing issues, inspecting and manually changing the channel might solve the problem. Path to router settings depends on the software, which can be accessed by entering the router IP address through a web browser. Most routers have an IP address of http://192.168.0.1 or http://192.168.1.1, or sometimes http://192.168.1.254. In the router software, look for channel information, log in if required and change it. Do not choose 'next available' - skip at least five or seven channels, since their frequencies overlap. Note that narrowband uses five channels simultaneously, while wideband routers use seven. We recommend that you monitor the graphs within the Wireless Diagnostics tool to choose a channel that offers the best performance.

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Use the 5GHz band instead of 2.4GHz

The channels described above relate to the 2.4GHz band. If the methods did not fix the wireless issues, switch to the 5GHz band. The 5GHz band is less susceptible to interference, since other domestic devices do not use that frequency. It also offers more bandwidth as compared to 2.4GHz. Unfortunately, this option is available only for dual-band routers. If you use Apple products, AirPort Extreme and Time Capsule offer this feature. To begin, you must separate the 2.4GHz and 5GHz networks on the router and give them different names. For Apple devices this can be performed in the AirPort Utility application, under the Wireless tab. Click the Wireless Options button at the bottom of the window and enable the checkbox beside the 5GHz network name and set a different name to the other band. Finally, set the Mac and iOS devices to join the 5GHz network rather than 2.4GHz. On a macOS, go to System Preferences and select Network, choose Wi-Fi network, and click Advanced. Drag the 5GHz network to the top of the preferred networks list. On an iOS device, open Settings and tap on Wi-Fi. Next, tap on the blue 'i' in the circle beside the 2.4GHz network name and toggle Auto-Join to off. Finish by connecting manually to the 5GHz network.

5ghz-wifi-list

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Run Apple Diagnostics

If none of the steps above solve the Wi-Fi network issues, use Apple Diagnostics to check for existing troubles on the Wireless adapter or network. To use this tool, first disconnect all external devices, except the keyboard and screen. Next, shut down the Mac and turn it back on, but hold down D on the keyboard when turning on. Release the key when you see the window asking to select your language - select it and wait until the process finishes (this can take 2-3 minutes). If the tool detects any problems, they will be displayed on-screen together with suggested solutions.

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Reset your Mac's SMC and PRAM or NVRAM

If you still struggle to solve wireless network problems, try resetting the Mac SMC (System Management Controller) and PRAM or NVRAM. Detailed steps here: how to reset Mac's SMC you will find in this step-by-step guide. Process: how to reset your computer's PRAM or NVRAM is described here.

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Change the DNS settings for your network

Changing the DNS settings is a recommended method when dealing with network-related issues. This method may seem confusing, so follow the steps below. First, you need to delete your Wi-Fi preference files, but we strongly recommend that you create a copy, before deleting. Begin by launching Finder. Click on Go in the menu at the top of the screen and select Go To Folder. Type the following destination: /Library/Preferences/SystemConfiguration/ Within this folder, look for the files listed below, drag them to a separate folder where you will store them.

  • com.apple.airport.preferences.plist
  • com.apple.network.identification.plist
  • com.apple.wifi.message-tracer.plist
  • NetworkInterfaces.plist
  • preferences.plist

dns-settings-folder

Next, restart the Mac and turn on Wi-Fi to check if the problem is solved. Otherwise, create a new Wi-Fi network location adding custom MTU and DNS details. Before adjusting these settings, close all applications that might be using the network. When you have closed all apps, go to System Preferences and select Network. Then click the wireless network and click the drop-down beside Location in the top center of the window. Choose Edit Locations, click on add (+) to create a new location, and name it with something you can remember. Finally, click Done.

new-location-mac

Next join the Wi-Fi network using your usual router password. Click Advanced, select the TCP/IP tab, and then click Renew DHCP Lease.

renew-lease-dns

Go to the DNS tab and add 8.8.8.8 and 8.8.4.4 addresses to the DNS Servers list (those are Google's free DNS servers, but you can add any you prefer.)

dns-servers

Next, choose the Hardware tab. In the drop-down menu next to Configure, select Manually. Change MTU to Custom and set it to 1453, click OK, and confirm by clicking Apply.

custom-mtu

If none of methods above solved the wireless network issues, consider replacing the router.

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About the author:

Tomas Meskauskas

I am passionate about computer security and technology. I have an experience of 10 years working in various companies related to computer technical issue solving and Internet security. I have been working as an editor for pcrisk.com since 2010. Follow me on Twitter to stay informed about the latest tech news or online security threats. Contact Tomas Meskauskas.

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