I have an extremely tough problem that's hard to chase down.
My father-in-law, George, has a Mac Book Pro here in the USA that he bought this year (2016) with Yosemite on it from Best Buy. I haven't yet upgraded his OSX. I have a Mac Air 13" that I bought from Apple in 2015 with Yosemite on it and then upgraded it to the latest OSX.
I have DSL high speed Internet at my house. George, however, has Time-Warner Cable and has purchased a custom cable modem NAT router with WIFI from WalMart for each of his Time-Warner locations -- one at the beach house, and one at his house. He has one model from Motorola and another from NetGear.
When I use my Mac Air at my house, I never lose a connection to my WIFI router. However, when I am at his house or the beach house on Time-Warner Cable, my Mac Air has an issue randomly every 4 to 10 hours where it loses the Internet for whatever reason, but the quick fix seems to simply be to bounce the WIFI to off and then back on again.
George, as well, has this same problem with his Mac Book Pro laptop, and resolves it the same way. It occurs at two separate locations with Time-Warner Cable. Also, when his laptop goes down, so does mine at the same exact time, when we are at his house or the beach house with Time-Warner Cable.
We had Time-Warner Cable come out to look at the line and they said indeed there were some issues at his regular house, but not the beach house, and they repaired it. Now the modem doesn't have the issue -- it's just the WIFI connection to it, which we can bounce (WIFI on/WIFI off) and within seconds we're back in action again.
The reason he has two different router vendors (Motorola and NetGear) is because we thought perhaps it was router.
He's come over to my house with the DSL and never experienced a lockup, and, I'll say again that I've never had a lockup on my house WIFI with the DSL, either.
So I tried changing the WIFI speed on his two cable modem routers so that they weren't the highest possible speed. That didn't seem to have any effect. Then, I changed the channel on each router and used an app on my Android mobile phone that told me which channel would have the least interference. I also ensured he had no cordless phones in his houses that might be impacting this. The net effect of these changes is that they showed no improvement. I kept changing channel for awhile and nothing seemed to fix this. His laptop WIFI and my laptop WIFI will intermittently lock up on his Time-Warner Cable Internet every 4 to 10 hours, but simply bouncing the WIFI signal fixes it instantly.
So I ran the WIFI diag wizard (alt key + WIFI menu) on his laptop and mine and it found no issues.
The only things consistent in this problem are:
He's not paying the outrageous fee for their Time-Warner brand cable modem. Instead, he's using one from Walmart. (Two, in fact -- one from NetGear and another from Motorola, one at each house location.)
He's using Time-Warner.
It's got the same symptom at both house locations, whether it's his Mac Book Pro laptop or my Mac Air 13" laptop. (And it never happens on my telephone DSL Internet.)
Is this problem a well-known Mac problem? Or, is it a well-known Time-Warner scam where they want to force you to purchase their own brand of modem? Or, does Time-Warner just go down every 4-10 hours for like a second or two? Or is it something else?