The first thing you should know is that Lenovo has acknowledged the faulty Wi-Fi cards contained in their Ideapad U310 and U410 models, resulting in a class action lawsuit. If you purchased your device before September 15 of 2014, then you are eligible to make a claim. To do so, visit https://www.lenovolaptopwifisettlement.c...
Otherwise, you first need to 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.
From here you can follow Lenovo’s Wi-Fi troubleshooting page here: https://support.lenovo.com/us/en/documen...
Also take a look at the Lenovo Ideapad U310 Troubleshooting page here on iFixit: Lenovo IdeaPad U310 Troubleshooting
Hope this helps!