You're using the wrong software. I used to work for a company that makes POS software, and:

• It's supported ipv4 for probably 20+ years
• Hosted customers were moved to AWS by 2019
• Latest GUI requires at least 1024x768, higher res is fine (there was only TTY in 1993, though)
• Offline mode is supported
• Printers were usually USB

Omfg the tap commercials confused the hell out of old people, and every fucking day I have some crotchety fuck smack my machine with their card then get mad at me when it doesnt work. I literally once had a customer call me stupid because he couldn't figure out how to hold his card still for five fucking seconds. Every transaction I tell these people to "hold your card right there and wait for the beep." And then helplessly watch as they wave the fucking thing sort of close to the sensor and then pull it away too soon only for the machine to say, "card read error" and then they look at me silently asking, "did it go through?" No it did not go through. If it went through it would say, "Approved" but instead I now have to tell you for a second time how to hold your stupid card. Oh youre just going to insert the chip? Perfectly fine, go right ahead that might even be faste— why the fuck did you hit cancel?

what is point of sale?