IP is always your best bet as it cannot be confused.
The slash at the end is only for accessing the web interface via browser as it hinders them from automatically redirecting to the Google search. So when using the Playername, only use the exact wording as in your Playername field.
Naming the port is also not necessary.
Issues with resolving the playername might be connected to your home network’s parsing of your player name or other devices in your environment.
You can try renaming your device to see whether this solves the issue.
However, having the IP entered should not be a problem and would definitely work, which is why we added it as an automatic example next to the field. Why do you want to avoid using the IP?