Unhappy [Q] WiFi not turning on and other problems

A relative has recently given me there Note 10.1 2014 LTE (Model number: p605) which is currently encountering some issues, in the hope that I will sort it out for them. The issues are all to do with the WiFi.

The device has absolutely no modifications, and running the stock ROM. Here is a screenshot from the "About" section:




The problem is that WiFi sometimes refuses to turn on. You slide the toggle, and then it just turns grey:



After a minute or so, it will then return to the off state. The funny thing is, rebooting the tablet will temporarily fix the issue, allowing WiFi to be turned on again. However, once idling for a few hours, the issue will return.

My relative says that this issue never happened on JB, but only started happening once upgrading to KK. So my question is: have any other p605 owners experienced this? If so, how did they fix it? If nobody has experienced this, could anybody recommend a good way to fix this? I was thinking about a factory reset, but this should be a last resort, as they really don't want to loose all of there data!

Thanks for the help!

Sent from my Nexus 7 2013, Running Android L