You need a domain to resolve to an IP and the port needs to be open for Traefik to be accessed.
Enable and check Traefik debug log (doc) and Traefik access log in JSON format (doc). Are requests showing up?
For TLS to work you would usually buy a TLS cert or use LetsEncrypt for a public domain (at least public root domain). For those the CA chain cert is present in OS and requests to sites with such cert will be trusted by client.
The TLS errors you see are just a debug info (DBG), some client is trying to connect without the matching CA chain cert installed. On public Internet this happens all the time when some bots try to access.
If you create your own custom cert, you need to make sure you have the CA chain cert imported into OS or the browser. This is of course not a workable solution for public sites.
Note that loadbalancer only uses protocol and domain, not the path. Path is taken from original request unless rewritten with middlewares.
Finally note that you can’t change Traefik dashboard to be accessed by / only (removing /dashboard).