Other than how to work a large event, I think the question I get asked the most is "How do I keep my professional and personal lives separate?".
Short answer? You can't. Not really.
I don't mean you should want to take everyone you meet home for dinner. But you should be at least willing to have a social coffee with them, even if the conversation revolves around business or career issues.
If you're not willing to share even the smallest personal details about you and trade a few stories, you're not going to see much reciprocation in your other asks. It's a grey zone for sure - but one you can easily manage. You just can't avoid it.
I really believe there is something to enjoy about most folks I meet. Sometimes I have to dig for it (lol) but finding a point of connection always works out for both of us.
And grey zones aren't just about those we would rather didn't cross our paths. Eventually, many mentor/mentoree relationships evolve into friendships and/or business opportunities. You then know a great deal about each other and you have to manage the boundaries more deliberately.
Sincerity in networking requires a crossing into the grey zone too. If you ask me how I'm doing but don't really care or listen to my answer - skipping ahead in your mind to what I can do for you - then I'm not likely to play in your sandbox.
So it's personal. You'll run into each other in line at the coffee place. You'll care enough about your contacts in ways that will range from "Let's have dinner" to a personal email that says "I heard the news...".
My November post - Please Like Me may be the most controversial posting I've written in light of this question! Why spend any effort avoiding connecting with people if you really wish to build a community?