How do I really network at work?

I’m currently interning in a not soo good role at a Big BFSI company, but I rarely interact with others. My assigned team sits in a different office on the same floor, and I’m surrounded by people from other departments. The Treasury team next to me works on something interesting , and I’d love to intern there if given the opportunity. My company has several departments like Strategic Planning and Credit Risk, which also interest me, but apart from connecting with people on LinkedIn, I haven’t interacted with them at all. Most of the times, I have lunch alone, and the "networking" which most people talk about isn’t really happening. Should I just mind my own business, focus on my work and leave, or should I make an effort to connect with people in other roles? I do want to know more about different functions and possibly improve my chances of rejoining the company in a better role in the future. Any advice from you all on how to go about this would be really appreciated!