If a windows machine, specifically a laptop, is having trouble connecting to the wireless, or has trouble holding on to a connection try changing the power plan.
1. Go to the windows taskbar and click the battery icon. Select more power options
2. Show additional options and select High Performance.
Typically most laptops are set to balanced mode when on battery and not plugged. Because it is using less power to run the parts in the laptop the wifi card may not be drawing enough energy to connect effectively.
This was taken off the Apple Support page about Wi-Fi not connecting. https://discussions.apple.com/docs/DOC-3411
If you find that your Mac is having trouble reconnecting to an AirPort base station by wireless after either it has been sleeping or after a restart, please try the following, in order, until (hopefully) resolved:
1a. Delete Preferred Network(s)
- System Preferences > Network > AirPort > Advanced > AirPort tab
- Under "Preferred Networks," delete the network(s) you regularly use from the list.
1b. Delete AirPort Keychain Entries
- Launch the "Keychain Access" application located in Applications/Utilties.
- Click on the "Kind" filter at the top, and look for any "AirPort network password" entries...and delete them.
1c. Add Preferred Network(s)
- System Preferences > Network > AirPort > Advanced > AirPort tab
- Add the preferred network(s) using the "+" button.
- Restart or log out then back in.
2. Move System Configuration Files
(Note: You will have to reestablish your network connections settings.)
- Go to [Macintosh HD]/Library/Preferences
- Move the SystemConfiguration folder to the desktop.
- Restart your Mac. (Note: OS X will rebuild the files that are now sitting on your desktop. If this doesn't resolve the issue, you can move the folder back to it's original location.)
Check Your Mac’s WiFi Settings
The first thing to do when you’re experiencing WiFi problems is to check and validate your network settings in System Preferences to make sure everything is setup correctly.
1. Open System Preferences and select the Network icon, which is in the Internet & Wirelesssection
2. Click the Advanced button at the lower right to view more details about your network connection
3. Under the TCP/IP tab, under most circumstances you’ll need the Configure IPv4 item set to Using DHCP. The reason is that in OS X Lion there have been some reports that manual configuration causes issues (though this may only be with early versions after the OS was first released)
4. You should also look at the other network tabs such as Wi-Fi, and check that the network you want to join is shown in the list. Drag the networks into the desired order, for example you may as well move the network that you want to connect to right to the top of the list to make sure your Mac looks for that one first
It’s also definitely worth just plugging in a network cable between your router and your Mac, to check whether basic Internet connectivity is working. If you can’t even connect to the Internet with a cable, then it points to a broader problem that may not be related to WiFi.
Remove and Re-Add The WiFi Service
One thing to try when you’re experiencing wireless network problems is to delete and then re-add the WiFi service.
Follow the steps below:
1. Open Network settings under System Preferences
2. In the left-hand side panel, select the Wi-Fi icon and then hit the Delete button (the small “-” icon) and confirm when prompted
3. Once the WiFi service has been deleted, add a new one with the Add (“+“) button, and then enter the name of the new connection followed by Create. This establishes a new WiFi connection with the default settings. Just go through the various tabs to make sure WiFi is configured correctly (items such as the password) and try connecting to your wireless hotspot again. If prompted, re-enter any details that may have been lost when deleting the service
Check Your Wireless Router Settings
Your wireless router is normally provided by your Internet Service Provider (ISP) when you sign up to an Internet, phone or TV package. Sometimes however it’s necessary to reset the router (there should be a small reset button on the back), or even login to it and play around with the settings to use the optimal configuration. Unfortunately, quite often the administrator password isn’t provided to customers to stop them changing the default settings accidentally. If you know the password, it’s definitely worth logging in to the router to inspect the configuration.
To get to your router, open a new tab in Safari and enter the following address in the address bar:
This should take you to the router’s login / administration page where you need to enter its admin user name and login password. If this address doesn’t work, you can try one of the other default addresses commonly used by routers, such as 192.168.2.1 and 192.168.1.1
Make sure that you take a look at the security settings (such as the wireless key) and inspect the logs to see if there are any clues about potential issues. Every router is different, so there’s not one set of specific instructions that works across all models, but in general a few tweaks can usually help resolve your WiFi connection issues. For example, if there are dozens of WiFi hotspots in the area where you live, you might be subject to wireless interference issues if someone else has configured their router to use the same wireless channel – try changing it from the default channel to something different. You can also change the security settings (for example to use WPA or WPA2) or remove them completely, to see if that makes a difference.
Try Connecting Other Devices
It might seem pretty obvious, but you should always try connecting another device over WiFi to see if it’s actually your Mac or the wireless network itself which is experiencing technical issues. If you can successfully connect another computer, iPhone or tablet for example, then it points to an issue with your Mac rather than the network kit or Internet connection.
Also, you should of course try connecting your Mac to another wireless network to see whether the problem persists. If you can connect to another WiFi setup, then consider noting down the router’s configuration and setup details and comparing that to your own.
Reset PRAM and SMC
Your Mac’s Parameter RAM (PRAM) memory can occasionally be the cause of various technical issues, so if you have WiFi woes and nothing seems to work you could try to reset it. Follow the procedure below:
1. Shut down your computer
2. Locate the Command, Option, P and R keys. You’ll need to use these in a moment in step 4
3. Turn on the computer
4. Press and hold down the Command, Option, P and R keys before the grey screen appears
5. Hold down the keys until the computer restarts and you hear the startup sound for the second time
6. Release the keys
The PRAM should now be reset to the default values. Try connecting to the Internet by WiFi again when your computer has fully rebooted.
Another approach is to reset the main SMC chip (System Management Controller), which may resolve issues related to fans, lights, video and power. If you’ve tried everything else and you still can’t get your WiFi to work, you may as well reset the SMC, as there aren’t any negative consequences of doing so.
1. Shut down the computer
2. Plug in the power adaptor
3. Press the Shift + Control + Option keys and the power button at the same time
4. Release all the keys and the power button simultaneously
5. Press the power button to turn on your Mac
Delete The Internet Preference Files
You can try deleting some of the Internet preference (.plist) files from your system Library folder. Sometimes, corrupted preference files can be responsible for things not working correctly. Follow these steps:
1. In Finder, press Command + Shift + G and in the drop-down dialogue box, enter ~/Library as shown below:
2. Locate the following preference files
3. Copy the files somewhere (e.g. to your desktop) as a precaution and then delete them from the Library folder. Any similar files named com.apple.internetconfig[...] can also be safely deleted
4. Turn your Mac’s airport off and back on (just click the airport symbol in the menu bar and choose Turn Wi-fi Off)