Internet out and freezes

I've never experienced Internet problems causing freezes. Is this possible, or merely a coincidence? All PM yesterday I was subject to multiple freezes, and Internet outages, but not necessarily concurrently. I went to bed last night resigned to the idea that I'd do a wipe and install, but today, miraculously, all is well, 4 hours into my surfing session. It got so bad that it froze at the login window. It also froze in Safe Mode, which I didn't know was possible. I have Yosemite, but this started a day after the install, and I don't think that's the problem. Imac from Aug 2012 (mid '11).