I’ve been hammering it hard rn and it definitely is the Unified Push / DHT proxy. The instant those are disabled, it works reliably. So I may need to revise my position.
The thing that really caught my attention is the jami daemon
docs.jami.net/en_US/user/jami-for-servers.html
If I’m reading that right, it’s sort of like a headless instance that can store and forward. Additionally, it doesn’t require tail-scale / head-scale to do so (as jami has its own protocol). So no nonsense with domains, reverse proxy, certificate infrastructure or public chat service.
The only issue is “it’s not self hosted”, which was part of the brief.