Acer laptop won't connect wirelessly

The only device in our home that won't connect to the wifi wirelessly is my son's Acer laptop.  We have tried updating drivers, and it works if connected directly via ethernet.  Xfinity says to call Acer, Acer says to call manufacturer of modem (Technicolor?)  I've spent HOURS trying to figure this out.  I saw others have posted a similar problem but no clear answer was posted other than what we have already tried - please HELP!