I'm posting this as a hope that it will help some of the many folks viewing this and similar threads. I've just spent the last four months (off and on) trying to figure this problem out. I've read every thread I could find and tried every "solution" out there. My own situation will, of course, involve different computers/mobile devices/router, etc. than any of you, but the one similarity I have noticed is that we all seem to have only one or two computers that get randomly dropped from our network while everything else works great. And in my case, the computer that won't stay connected at home connects perfectly when I travel!
For me, I actually collected every device we have in our house that connects to the network, identified each MAC address, and set up MAC filtering. I also set up ip address reservations for all, and set each device to static. Overkill? Maybe.
But I persevered, as I am a work from home gal, and MY computer, the only one that actually earns its keep, was the one that would disconnect every time the kids or dad came home. I couldn't stay connected on the weekends without bumping them off.
So, one at a time, we tried things. Finally narrowed it down to three devices causing problems. My daughter's Galaxy Media Player, hubby's Galaxy Note, and hubby's Toshiba Thrive tablet. (Meantime, two Kindles, an iPad an iPhone & a Roku box cause no problem!)
Once I figured out how to set the Galaxies both to static ip under their settings, they stopped causing a problem. The Thrive Tablet, however, is another story. It will not hold it's Static IP setting, and so everytime hubby left home and came back, it would have to be reset or it immediately took over the network from my laptop. I have researched this issue with the Thrive ad nauseum, to the point that I decided that perhaps I needed to let the ip address reservations go and ditch the static ips. I mean, you can, sometimes, have too much of a good thing!
Bottom line, with the MAC filtering set, I'm not having any problem except with the Toshiba Thrive. Which, at this point, I think we'll sell and replace with an ipad!
Here is the thing, if you haven't checked out all the devices that attach to your network, you might want to do so. We're shockingly well endowed with wifi suckers at our house - four people, 12 devices on when we're all home, and two more sporadically when my parents come for a visit. We live out in the sticks, have an unsecured network 'cuz no one lives close enough to pick up our signal, but that also cut out a lot of the potential interferences for my troubleshooting. So do yourself a favor and take everything else off line, see if your problematic connection clears up. If it does, reconnect one device at a time to see if you have a conflict between devices!