I'm having better luck at focused technical discussion on Stack Exchange rather than Reddit. I've found a few non-technical subreddits of interest though. For that, it's been a pretty phenomenal community builder. Better than any other forum I'm currently aware of, HN included (though HN's focus on tech and the startup world is pretty good).
Farmsteading Reddit seems to work reasonably well, though it takes time to generate traction. Seed, fertilize, and weed.