MoP private servers require an unlocked/patched client executable file to allow custom realmlists. Download a clean WoW 5.4.8 patched.exe file. Managing Playerbots and Custom Rates (Optional)
Double-check your realmlist.wtf file contains exactly set realmlist 127.0.0.1 . Also verify that authserver.exe is still running (check your taskbar or process list). wow 548 repack work