To grow your professional network I would recommend to attend to meetups, hackathons, user groups or even better to get involve in the organization. It worked pretty well for me.
I met some incredible people and got some good jobs offer.
Everyone of these meetups I've been to feels so...forced? I don't know but I've never really felt comfortable at these kinds of things. It's always so contrived?
The problem is that people in your network are often, well, in your network so if you haven't exhausted your network already, you wouldn't be posting online asking where to look for jobs.
I think for people who aren't naturally social butterflies, networking should be thought of as one of, but not necessarily the best or most efficient of, the ways to force the job search process. For people who just like to socialize with people in their field, networking might be strictly the best way to find work.