This article describes why the HDMI port may be missing on the Elo 1517L / 1717L

The Elo 1517L and 1717L monitors were revised in 2021 to add a video interface with an HDMI port. Units manufactured prior to this hardware revision were equipped with VGA only and do not include an HDMI connector.

If your 1517L or 1717L does not have an HDMI port, it was most likely produced before the 2021 update and is a pre-revision model.

For full details on the hardware change, refer to:
PMB 734 – Product Notice: 1517L / 1717L HDMI Revision
https://elosupport.elotouch.com/hc/en-us/articles/31651208817303-PMB-734-Product-Notice-1517L-1717L