Remote doesn't show up as a plugin but it should still work (at least it does for me on 3.1.1). If you go to the configure / Remote Interface it will show the installed version and allow you to check for Updates.
Try to connect to the remote interface by scanning the QR code on your mobile and if this doesn't work try to connect using a browser on the machine running OpenLP. If this does work I suspect your firewall is not configured correctly.