@MartyFouts @danyork With the hint that it was a Dreamhost issue, I found this: https://www.sidhe.org/blog/2023/09/23/setting-up-the-activitypub-plugin-on-a-dreamhost-vps-hosted-wordpress-blog/ - I'm on VPS on Dreamhost, and the instructions worked. @blog is up and running. Haven't tested a post yet, but I was able to follow it. Yay!