This guide is a personal reference used when deciding on an APC UPS.
APC UPS Network Card Compatibility:
The following website is the official APC compatibility list: https://www.apc.com/au/en/faqs/FA237786/
Note that even old devices support most forms of SmartSlot cards. See the following link for a list of SmartSlot cards on Wikipedia:
(Please note that not all of these cards are IP networking cards, please check their descriptions) https://en.wikipedia.org/wiki/APC_Smart-UPS#SmartSlot_card_models
The first model of SmartSlot card that supported 10BASE-T networking was the AP9605, released in the mid 1990’s, so assuming your UPS was built after then, and support SmartSlot cards (Identifiable by the removable rectangular black bracket on the UPS), you are more than likely able to use a network card.
Note that Dell branded APC UPS units contain the suffix “DLT / DLA”. These UPS units are mostly the same as the SUA / SMT versions of the APC branded devices.