My first guess is that using an actual hostname isn’t going to work for you if that hostname is served by your local network DNS (meaning, not using magicdns on tailscale), which you would not be on when connected via tailscale unless you override your DNS server once connected.
Try by IP instead. Give errors if that doesn’t work.
Then you need to ssh into both devices and confirm they can both ping each other via the tailscale interface as a starter. That will at least shownif you have a routing problem.