Ultron got to Sokovia from Shield headquarters via the internet. Why didn't Vision follow the same path through the internet to destroy Ultron from within?
That way the Avengers wouldn't need to ever physically interact with Ultron.
We see Vision destroy Ultron's presence on the internet in a later scene shown below.
Vision could essentially take back all of Ultron's bodies, so to speak, providing Shield with an army, Ultron's army. 0:15 - 0:38
As we know that being born rightaway, Vision was suffering through an identity/existential crisis, figuring out what he is, his purpose, reason for existence etc.
The conversation between him and the Avengers showed that he is on the good side, and the conclusion of the meeting was that 'Ultron must be destroyed'.
Destroying Ultron through the internet was never an option or a possibility,Vision became a part of the team which was going to fight ultron and shut him down for the survival of human race.
In the fight scene, we see Vision trying to shut down Ultron or whatever, but that was possible only via physical contact.
In short, no method/procedure was shown in the movie to shut Ultron down via Internet, Ultron was only using Internet and its resources and what all that can be done, ranging from accessing secret S.H.I.E.L.D data to making net-transactions.
From the movie script:
Vision: What will you do? [he looks at them all realizing they will destroy him] I don't want to kill Ultron. He's unique, and he's in pain. But that pain will roll over the earth, so he must be destroyed. Every form he's built, every trace of his presence on the net, we have to act now. And not one of us can do it without the others. Maybe I am a monster. I don't think I'd know if I were one. I'm not what you are, and not what you intended. So there may be no way to make you trust me. But we need to go. [he holds up Thor's hammer and hands it to him, Vision walks off and everyone stares in shock]
As you can see, he does speak about the fact that he can't simply do that alone, most probably because Ultron isn't only on the net but also in several physical forms. If he's deleted from the net without disabling those bodies access he will simply "re-infect" the net. It's shown in the movie that the way Vision shuts him out of the net is by interacting with his primary physical body at that time. And even that is hard enough to make Vision pass out even though Ultron's body is still fine, so he obviously can't do more than that, like shut off every other body at the same time as well.
