Arma Reforger: main game or Experimental?
Understand why two Reforger applications can appear in your library and why the selected version matters.
Choose the intended application
Bohemia distinguishes the main Arma Reforger application from Arma Reforger Experimental. The main game is the regular release; Experimental is used to test developing features and gather feedback. It is a separate application with a different game version. Before joining friends, check the full application name in your library and agree on the build you are using, rather than assuming every Reforger installation connects to the same sessions.
Check the server and its add-ons
Bohemia states that Experimental and the main application are not mutually compatible. Its documentation also explains that changes between versions can affect mods. When joining a community, follow the server’s stated version and add-on requirements. If something fails, record the application name, version number and active mods before asking for help. Those details are more useful than simply reporting that an Arma server will not let you join.