Yes, exploitable land can be owned by an individual in a socialist economy. If you're growing food for your family, then that's just one family the state doesn't have to feed. If you're growing food for your community, then that's several mouths the state doesn't have to feed. If you're hoarding or selling food (or in one very famous historical case, burning it out of spite), then you are monopolizing a resource that could be feeding people, and the state will intervene, whether by buying your land back from you, taking it from you, liquidating you as a class, or some other solution to be determined by the state in question - there is no one size fits all blueprint to socialism.

What I never quite understand/know is where internet based services land. If I run a cloud based storage company / web design company or such, the servers are on my personal property and therefore should be considered allowed. Where does that start becoming non "personal."

It's like charging someone to park their ideas/data on my personal property. Which I imagine would be considered private property instead. Where is the nuanced line?

Anyone care to explain?

If you keep more than you need, yes. Socialism is not about hoarding wealth especially in the form of necessary goods.

Socialism is when you don’t have to do alienated work. And when noone else has to. Of course the productivity will be higher if you share the means of production with others. But it’s perfectly fine to work on your own too and harvest the fruit of your work. As you know, nobody gets rich by his own hands work, but you can get along. Capitalist exploitation starts when other people work for you and when you take the added value for your own benefits.