May be beyond my pay grade, apologies, as I do not know Tailscale.
I might suggest viewing your Haven logs as you should see a log if notes are received, or trying wss rather than ws, or trying a reverse proxy.
GL
Yes, in a browser on my laptop (or phone): http://mytailscaleaddress:3355
hits the outbox end point from anywhere.
Also, Coracle and Damus show green light/connected when the relay is added (ws://mytailscaleaddress:3355) to those clients.
I've posted a note but Coracle shows connections: 0 to the relay.
Discussion
Yeah, the logs just show the initial startup of Haven, which all looks good, then nothing after that. I mean, these comments should be sent there right?