How contagious is it? Can I get other people banned from Reddit by logging into my instantly banned account on their wifi network?

Not that contagious, I'm afraid.

My boss uses Reddit some. I'm banned. At the shop, we use the same IP address (and we do not use ipv6 there).

I tried to log in with a ~10-year-old account that I'd never commented with. A perfect Beetlejuicing moment had arrived and I just wanted to play the game with a short, snarky comment.

It logged in fine, and then: Insta-ban, just like that. (Maybe I should have used a new browser on a new network that I've never used before, but whatever -- nothing of value was lost here.)

Meanwhile, the boss man's access continued unimpeded; this suggests that it is a rather targeted contagion.

And it seems to follow the systems, not the networks.

(If anyone wants banned, just let me know. I seem to have a well-poisoned system to play with.)