Set up Tailscale as exit node to your local network.
Make sure that your network is not standard 192.168.0.x or 192.168.1.x IP address range, but something like 192.168.101.x so you don't have IP conflicts when accessing from a friend's house or workplace wifi.
Set up Nginx to redirect your home server IP (eg. 192.168.101.5) to the correct port for your dashboard like Heimdall or Dashy.
That's it. Works like a charm for me if set up this way.
Addendum: if you have trouble on Android, disable MagicDNS.