First of all, are you trying to print from the iOS 15 iPhone 7 mentioned in the equipment line, or possibly from another device/computer? Exact information about the devices/computers involved, and about how they are connected, would help.
The Epson ET-2800 is listed as a supported AirPrint model in About AirPrint - Apple Support. This means that it should be possible to print from an iPhone without an extra app (or from a Mac without additional drivers), provided that the printer and the iPhone (or a Mac) are connected to the same network (Wi-Fi router).
Without knowing any details, a first troubleshooting step could be to try a full power-cycle sequence (do not forget the router).
- Power off the Wi-Fi router, the printer, the iPhone, any Mac, and all other devices/computers.
- Wait two to three minutes.
- Power on the router.
- Wait two to three minutes.
- Power on the printer.
- Wait a minute or two.
- Power on the iPhone, any Mac, and all other devices/computers.