The hardware is excellent for thermal labels. The printing quality at 203 DPI is sharp for barcodes and addresses. However, the WiFi implementation is clunky . It is clearly a USB printer retrofitted with a WiFi dongle.
(often called "Xprinter Diagnostic Tool" or "Tool.exe") from the Xprinter Application page 3. Configure Wi-Fi Settings Printer XP-420B - Skynet xprinter xp-420b wifi setup
Once you have the Xprinter XP-420B connected to WiFi, maintain stability with these tips: The hardware is excellent for thermal labels