Q: MBP dropping internet connection

Hi

My wife has a MBPro late 2011 running latest OS system.   For some reason this laptop keeps disconnecting from our home LAN wifi connection.  My MBP - mid 2012 is perfectly OK.

Her laptop only has our two wifi networks, our 2.4GHz and our 5GHz.  the DNS is set to the same IP as the router 192.168.1.1

Any help much appreciated as I am getting a lot of grief on this

Thanks