Working configuration for printing 4x6 labels (eBay shipping labels, etc.) to a Godex RT730i over Ethernet from Kubuntu, using Godex's own rastertoezpl CUPS driver (EZPL, the printer's native language).
Printer: Godex RT730i, firmware V1.130, direct thermal, network address 10.1.6.46
Host: Kubuntu 26.04, CUPS with AppArmor confining cupsd
Driver: rastertoezpl-1.1.2 from the Godex downloads page (Linux CUPS driver)