How to diagnose Default Print Service problems on GrapheneOS

dln949

Pixel 6A running latest version of GrapheneOS/Android 14.

I'm trying to print from the GrapheneOS phone to a networked printer on the same internal/home wifi network that our personal phones use.

I'm looking at two phones in our home. One phone is running the /e/ OS (Android 11) on a Pixel 4 XL. Its Default Print Service shows three printers on our home wifi network that I expect to see, and I can print to them from that phone with no problem. The other phone is the GrapheneOS device. Two of the printers do not appear in its Default Print Service. (I have a photo of the two phones side by side that make the differences very plain, but sadly I can't figure out how to upload and attach a photo to this message.) In case it matters, on the GrapheneOS phone it didn't matter if a VPN was on or off, nor did it matter if in airplane mode or not.

Why does the GrapheneOS Default Print Service not show two of the three expected printers, while the Default Print Service on the /e/ OS device shows all three?

How do I fix this problem?

Thanks in advance.

datamorgana

I have a Pixel 8a with GOS/Android 15 (build 2024111800) that has the same problem, I think. Configuring the printer service system app seems easy at first sight (I can enter the URLs of my CUPS server and two separate printers), but on printing, none of the printers can be found. When tapping "All printers", the printer service system app is searching forever. My other phone (Motorola G7 plus with LOS 21), however, can find and print on all configured printers.

datamorgana

datamorgana I forgot to mention that the phone is able to reach the CUPS URL of both printers via a browser, like e.g. https://x.x.x.x:631/printers/printer1 but the printer service app isn't, apparently.