Computer is very slow< also a low signal on WI FI

try changing the wi fi channel to manual and make it 3 or more channel number higher in the wi fi router.
There may be other wi fi networks competing for the auto channel .

Sounds like weak signal problem or slow wi fi speed. Locate your wi fi transmitter as high as possible. Also check out your wi fi speed to make sure it isadequate for your service.

Make sure Wi-Fi is turned on your device
Make sure flight mode is turned off
Make sure your selecting the correct wireless name in range and using the correct network password to connect, Wireless networks with low signals will show connected but you will not be able to browse the internet
Check your router and modern, Make sure the lights are as mentioned in the user guide of your service provider
First figure out if the problem is with your Lenovo Device or the Wi-Fi network:
Device/Machine problems: Try connecting to the Wi-Fi network with another device, like a laptop computer or friend's phone. If any other devices can connect to and use the wireless network, the problem is most likely specific to your device.
Network/Router problems: Check to see if your device can connect to a Wi-Fi network at another location, like a friend's house or a public network. If it can, the problem is most likely specific to the Wi-Fi network.
Then try the troubleshooting steps below based on whether the problem is with your device or the network.

How many 'bars' are showing on wi-fi signal strength indicator (presuming you are using wi-fi for internet access)? If the signal strength is low, you could be losing connections that way, or there might be interference on the wi-fi channel that the tablet is using. Try changing channels in your wi-fi setup and see if there is an improvement in the behavior.

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If the signal strength is low, consider using a simple wi-fi repeater, or relocating the wi-fi router so it is closer to the Player

Here is 10 tips to boost your router signal...
http://lifehacker.com/5931743/top-10-ways-to-boost-your-home-wi+fi

Hello Jane,

When using a Wi-Fi network with your iPhone, you may occasionally encounter the following issues,Unable to locate or join a nearby Wi-Fi network,Weak or low Wi-Fi signal strength,Connected to Wi-Fi network, but unable to access the Internet.
Tap Settings > Wi-Fi and turn Wi-Fi off and then on again. Verify that you are in range of your Wi-Fi router or base station. Confirm that your Wi-Fi router and Cable/DSL modem are connected to power and turned on. Check whether other devices (portable computers, for example) are able to connect to the Wi-Fi network and access the Internet. Update your Wi-Fi router to the latest firmware.

either the wi-fi signal is low or you need to update the system if the system needs an update you cannot connect to a wi-fi signal i hope this helps good luck.