My wife and I both have M4 iPad pros. We have an Epson 3850 tank printer. My iPad will print emails, etc with no problem. Her’s will not, gets some kind of error condition on the printer which causes it to restart. Both are running on the same current level of iPad os. She can print from her phone without any problem. It seems to be a real head scratcher to me. This problem started a few months ago. The printer has done firmware updates from time to time but why would one of those cause one iPad not to work and another one continues to work? Anyone have any ideas about how to fix this issue?

What's the error on the printer? Printers are one of the dumbest devices so even something as being on a different wifi frequency (e.g. 2ghz, 5ghz, 6ghz) could cause issues. Maybe it's a specific file or file type? If all else fails try wiping/reinstalling iPadOS.

What’s the error message in the printer?

Otherwise -if not already- cover »the basics« 🤓:

1. Delete the Epson printer software from the iPP of your wife.
2. reset the printer via its control panel -> Settings > Restore Default Settings > Clear All Data and Settings
3. connect the Epson again to your network.
4. Reinstall Epson print software from the Appstore on your wife’s iPP.
5. Try printing from both iPPs

No idea if this will be of help or not, but when I have problems a printer (s):
I go toSettings, openPrinters & Scanners,Remove the printer that is giving me trouble, and thenAdd the sameNewPrinter to the list. This seems to solve most issues relating to three or four printers I use.

Settings / WiFi .... you should see your printer set up there. 'Forget' all networks that look like or resemble your home printer.

Check the same in your iPad Pro's WiFi settings and ensure your wife's is set up the same way.

Check the WiFi router settings via the Admin panel, if available. You may find her iPad's profile duplicated or corrupted.

the easiest way to get the Epson tank series to print (using Air Print) from your iPhone is to download the Epson Smart Panel app (there should have been a QR code on the quick set up sheet when you bought your printer).
i have an Epson tank model (different one, though), and after i installed this app and, importantly, gave it the necessary permissions, printing has never failed. you won't need to use it to print, but it helps to make Air Printing reliable. this will give your iPhone the ability to give Epson Smart Print access to your local network. (Settings/Privacy/Local Network)
this app may not however be available in all app store regions, i don't know.

the other thing that seemed to be important for me was to get the Epson printer itself to have the latest firmware.
you can not rely on the generic driver that apple's macOS will try to use for this printer. once you have downloaded and installed the latest firmware to your printer (using your mac), it will be a more reliable print between your iPhone and the printer. maybe you can also do this directly from the printer itself. in the long run, with Epson printers its always best to have Epson's 10 or 12 files in your Utilities/Epson Printer folder and initiate software updates from there. (talking about macOS, that is).

Marvel, that is a head scratcher!

I assume you've powered off the printer and her iPad — that is, completely shut down both of them. Then, restarted her iPad first, followed by the printer. (Or, maybe the opposite order could work.). It could take doing it twice.*

We have the exact same model of printer — it's a marvel. (No pun intended! 😎) We've been running for TWO years on the original cartridges. Prints incredibly quickly (jobs are done before I can even walk down an half flight of stairs to it). Its black printing is better than our laser printer. It replaced a Brother inkjet that ate cartridges like Pac-Man.

Both of our iPad Airs print to it without issue.

As to settings, I just checked and, as expected, do not find any printer drivers or printer choices in the Settings app, and definitely not under Settings, WiFi.

What you're experiencing is baffling. Is Epson support any help? Or, Apple's?

I tried the following, but it was a dead end. Still, it might give you some ideas of things to try or to check!

——————

If I start a print job on the iPad, e.g., this web page, I get the Print dialog box, showing me the comment thread's pages on the left, and a dialog pane titled Options on the right where I can select printers. I just tried this and after selecting the Epson, there's an Info button. Click on that to see supply info — but it also has an option to “Show Printer Web Page”. Wonder if that has any extra info — perhaps settings to tweak or that you could use to see if your iPads look the same.

Alas, when I tried it again, that choice disappeared! Weird!

Tried it with an email (your situation) and Show Printer Web Page opened a window in Safari. Unfortunately, Safari displays a HUGE error banner saying “This Connection is Not Private” with warnings that the website might be impersonating Epson local web page and recommends closing the page and not clicking through. So, I didn’t pursue it.

——————————

*I had a weird thing with my iPad the other day where the WiFi setting was blank! No name and no option to turn it on or off! Never seen that before. It required TWO full shut downs and restarts before it reappeared. That’d why I suggested doing the restarts more than once.

Well I fixed the problem by taking the advice of preparing the iPad for sale (removing all personal content and then restoring the personal content from the iCloud backup. Not sure how it ever got messed up, suspect a code bug with recognizing the printer after a firmware update but in any case it is fixed. Thanks for everyone who offered help.