Try to install additional drivers:

Open terminal and do

List the network devices find the name of the WiFi interface.

sudo nmcli device

returns:

DEVICE           TYPE      STATE      CONNECTION 
wlp58s0          wifi      connected  ShareWiz         
lo               loopback  unmanaged  --   

Then do this command with your interface name.

nmcli -p -f general,wifi-properties device show wlan0

This should give you lots of info about it including what driver you are currently using.

If you want to switch to another driver then get it from here its in a.deb

https://launchpad.net/ubuntu/+source/backport-iwlwifi-dkms

Remove the driver that is currently being used:

sudo rmmod [drivername]

Then

sudo modprobe backport-iwlwifi-dkms

Not sure if its that or just

sudo modprobe iwlwifi