How to find a server that is consistent based on string (Server "name")?

I have 2 places. The lobby (limited to 1 player server), and the the gameplay place (not limited to 1 player). In the lobby, the user enters a string that chooses which server of the "gameplay place" they land in. There can only be one server per string. How could I achieve this?

I looked on the wiki and have not found a way to do this.

• The server in the "gameplay place" needs to know what string was entered