Does the Print portal correctly identify the printer?
If it does, you should have full options on print.
How does your screen look? (Assuming Android, hold Volume down and the power button to screenshot)
Mine for instance
I can simply touch Media Size to change to whatever the printer supports
But only because the printer (In my case an AltaLink) is known to the app, as seen here:
And selecting Printer Details <and wait a few seconds for it to populate>:
I got gifted one of these printers. I set it up, connected it via 1000mbit lan to my router and added it in Print Portal. I can't seem to be able to change the paper size anywhere in the application and it seems to be hell bent on printing Letter, despite the fact that I have set A4 as default everywhere in the printer.
Please advise. It has the latest controller firmware off the support section.