So first of all, I completely sympathize with you. I have been working from home for years and it's been a continual struggle. Some thoughts for you:

The biggest internet timesinks for me have always been those with near infinite novelty and also very occasional strong benefits.

For example, Reddit has clued me in on the Paleo diet and using a tongue scraper for better breath. Those have actively improved my life. I've also spent thousands of hours looking at stupid pictures. Hacker News has been more useful than Reddit, but still has been a large timesink. But we all have our own set of sites.

For me, blocking apps did not work at all, because I can just disable them. Unless I give up root access to my own computer, but that isn't really going to work. Having an "accountability partner" didn't work. I even did money challenges where I had to pay $500 to someone if I browsed Reddit. I did one time pay some money, and after that the group stopped really believing we'd hold each other to it.

Guilting myself has stopped working. But I don't think that's really a solution anyway.

Cold turkey seems to not really help. I'll go for a while without doing the addicting thing, and then get really angsty and then binge. Food can sometimes be this way this too. Yo-yo dieting and yo-yo internet binging both seem harmful.

Some things that have helped me:

First, just becoming aware of what is happening. I've been reading a lot about human psychology lately and came across the idea of "Supernormal Stimuli," the idea that some modern things are incredibly addictive because our brain did not evolve in an environment where it had to deal with things like the internet, Doritos, and internet pornography. This comic sums it up really well: http://www.sparringmind.com/supernormal-stimuli/

If you can in any way limit the sources of infinite novelty, or get rid of the worst offenders that can help. And I think all the sources contribute to make addiction harder to break.

And honestly not having internet at home did solve the problem - I've tried it twice. But I work only from home and kind of need it to do work. If I lived in a place that has better coffee shops, I might stick with that.

Speaking of which, leaving the house helps me. I find I am not as willing to just slack off completely if there are other people around, so I am quite productive in Starbuckses.

No electronics in bed has helped a lot. That alone has helped me not find myself staring at a device at 2am for no real reason.

Humans are creatures of habit and also lazy, and so one advice I've heard is to make the things you want to do as easy as possible and the things you don't want to do as hard as possible. If you can get away with not having internet at home, that might just be a way to solve the problem.

I don't think there is a silver bullet, but continuing to try things has helped me find a few things that have helped me. Also some of the above statements may not be completely accurate and I'm open to correction and further nuance.

Slowly over time I've seen myself become more and more self-controlled, though I'm of course not perfect. I'm convinced that the default today is for people to be addicted and ineffective since humans did not at all evolve in this sort of environment, and so anyone who makes an effort to better themselves can become very effective in life.

Best of luck, and email me if you want to talk more.