Quoted from Mk1Mod0:The printer (an HP from 1999 that still works great, yes I am a cheap bastard) is physically connected to another computer in the house.
The easiest way to solve this is connect the printer directly to the router instead of another PC.
If your router doesn't have a print server built-in one similar to this will probably work: https://www.newegg.com/Product/Product.aspx?Item=N82E16833704067