Can we regain control of our online time How hard would it be to break annoying habits when we isolate them Let's start our journey toward solutions by identifying problems clearly.

Problems

Number one timewaster in my Internet experience was chat. Still passionate about that enemy, I remember countless nights spent in chat rooms all over the English speaking world. Dial-up epoch... IRC client... lots of free time. Yes, some discussions were unforgettable; there was crying and laughing, teaching and learning. But, it was all writing in the sand of wild seashore. Nothing remained. Facebook without chat would not be that evil.
Second and third place is for games and porn. Both are time plagues offline too, both equally addictive. My online game was chess, and my favorite porn -- wait, let's change topic.
Fourth place in my list is reserved for any kind of news sites. There were month when I read every local papers, and also periods when I read none. For me, there was no difference. Except lost time.
Online articles are worse. Comments are often more accurate (more to reed), and sometimes they "require" our reply.
I don't know about you, but YouTube is number five in my list, along with all streaming videos and television. Particularly watch out for evil thumbnails "related". Ignore them like blinking banners, or you will get twenty more for every clicked one.
Forums are next, number six. On many occasions, time there is not wasted but invested. Writing wisdom in forums is much better than letting it fly into oblivion by chat, but it requires equally "too much" time.
At the end of this list is controversial seventh item: learning. Some say there is never too much of it. Can you lose time by watching tutorials, or by reading Wikipedia, blogs, books There is no universal answer, it depends of your goals and plans. When knowledge is presented in a tempting manner, who can resist it Adam and Eve did not.

Solutions

I see no other common denominator for items above than initial topic of the list: online activities. That could be enough.
Blocking online access should beat all threats. People with great self-control do not have time leackage. Good planning skills are helpful too. Such individuals are rare. Habits can only be replaced with other habits in complicated process which involve perseverance.
When you have made the decision, but don’t have enough will to uphold it, solution is a software tool.
Market offers applications for total blocking, Internet filters (blocking of predefined domains), blocking for predefined time period or predefined total amount of time. Some include all those functionalities and still are affordable.

Observations

"Block website" technique is rarely used for self-help. Instead, parents restrict online access to their children by internet filter while bosses do the same to their employees.
I prefer building character with no artificial aids. But if mu budget was not so limited, I would have considered using software for fast fixing of all overuse of online activities.
One way or the other, time is too valuable to be trivially lost.