I'm sorry to hear that the PayPal app is not working through your data connection. I agree that it's pretty strange to hear that it would work fine via WiFi but not when connected to your phone provider's data. I think the first stop would be to check with your phone provider to find out from them if there's anything they're doing that could present an impediment. If not, please go to https://www.paypal-support.com and log in and click Contact Us to open a ticket to our technicians.
I hope this can be resolved quickly!
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