You are confusing between being social and interacting with people in developing professional networks. Professional networks could be strictly career-oriented and collaborative with no personal attachment. Your professor, for example, is in your network and you do not need to socialize with him.

Coming to answering your questions. Why do you care about what happened in the past? Just start networking now. If you can find Linkedin profiles of those people, feel free to connect now with a nice message on LinkedIn. Though, I believe Germany uses some other professional network.

You build an academic network in many scenarios. For example, you discuss someone's work over email or in-person and exchange feedbacks. You can apply for funding together. Look for organizing conferences or some sessions in a conference together. Invite them to your universities for guest lectures and also get invited. Let the PhD students in the groups exchange ideas.

What do you gain from it? You get votes and citations to your work. People who know your work would probably be nicer when they review your paper and vice versa. Without going into many of those things, you can collaborate on interesting ideas and push the boundaries of science and technology faster than you would be able to do it individually.

Focus on these goals and networking will follow suit. Do not put the cart before the horse.

There are people of all ages in most events. And in Europe people are not as hierarchical as in Asia etc. So you can talk to even people who are more senior to you while showing respect. Eventually, it is those people who will give you PhD and Postdoc positions.

You are confusing between being social and interacting with people in developing professional networks. Professional networks could be strictly career-oriented and collaborative with no personal attachment. Your professor, for example, is in your network and you do not need to socialize with them.

Coming to answering your questions. Why do you care about what happened in the past? Just start networking now. If you can find Linkedin profiles of those people, feel free to connect now with a nice message on LinkedIn. Though, I believe Germany uses some other professional network.

You build an academic network in many scenarios. For example, you discuss someone's work over email or in-person and exchange feedbacks. You can apply for funding together. Look for organizing conferences or some sessions in a conference together. Invite them to your universities for guest lectures and also get invited. Let the PhD students in the groups exchange ideas.

What do you gain from it? You get votes and citations to your work. People who know your work would probably be nicer when they review your paper and vice versa. Without going into many of those things, you can collaborate on interesting ideas and push the boundaries of science and technology faster than you would be able to do it individually.

Focus on these goals and networking will follow suit. Do not put the cart before the horse.

There are people of all ages in most events. And in Europe people are not as hierarchical as in Asia etc. So you can talk to even people who are more senior to you while showing respect. Eventually, it is those people who will give you PhD and Postdoc positions.