Zebra GK420d
- Go to Windows settings
- Go to Printers/Device settings
- Select the Zebra Printer
- Click Printing Preferences, then the Options tab.
- Under Settings, set Speed to 4”/s (high speed)
- Under Paper Format, change to inches and landscape
- Under Size, set the width to 2.00 & height to 3.80
- Click the Tools tab
- Select Action → Calibrate Media
- Hit the Send button. This will use 2 blank labels.
- Click Apply to save your changes
Now print a test label from the portal.
Drivers
If you do not have the printer driver already installed, note they can be downloaded from Zebra website. Look for the Zebra Printer Setup Utilisies.exe application. Current link here: 
Zebra Printer Setup Utilities | Zebra
Zebra GK420d
Calibration instructions: Manual Calibration (zebra.com)
Bixolon SLP-DX220
Calibration Video: How to Calibrate a Bixolon SLP-DX220 | Smith Corona Labels (youtube.com)
General Troubleshooting
Clear printer spool:
start>run>services. msc.
locate print spooler, right-click and stop.
navigate to “c:\windows\system32\spool\printers” folder.
delete anything in that folder.
start>run>services. msc.
locate print spooler, right-click and start.
Delete persisting driver:
RUN: printui.exe /s
Connecting to ethernet accessible Bixolon
Static IP/MAC reservation for the printer - BIXOLON DX220
A port forward on port 9100 (TCP) to the printer IP.
Provide the external IP that we can use to install the printer from the cloud server
This is the IP of the server that the CDFpay is on for your school - ***.***.**.***
Once we have the IP of the Printer - we can configure your CDFPay Server.