Unplug the HDMI cable from your Mac, then plug it in again.Turn off the HDMI device while your Mac is turned on.If your Mac doesn't recognize your HDTV, display, or other HDMI device after making the connection: If using an adapter, check the specifications of the adapter to learn about supported resolutions and other details. Safari in macOS Sierra or later also supports HDCP-encrypted playback, if the web page is HTML5-enabled and the content is FairPlay Streaming-enabled and delivered using Media Source Extensions or HTTP Live Streaming.
Mac computers that have an HDMI port comply with HDMI 1.4b and support:
Learn how to identify the ports on your Mac. Mac computers that have any of the following ports can connect to HDMI devices.
