Unable to download files from Cloud on iPhone when on mobile network. On wifi download OK. NSFileProviderErrorDomain error -2005

I have files uploaded to the Cloud from another Apple device, such as Mac computer.

On my phone, I want to download the files from iCloud to my phone

If I am connected to wifi, the download works fine.

If on mobile I get "the operation couldn't be completed (NSFileProviderErrorDomain error -2005)"

label to sync with devices

Troubleshooting

I've turned off/on the phone

Under Apple Account > iCloud+ > Saved to iCloud shows Drive > Sync to this phone is ON

Icloud Drive shows 18 GB of 200 GB used

Documents and Data > Review Files > shows files, but same error results if I want to download. The could icon with an arrow downwards shows for files that fail to download.

Mobile > Files > ON (Green)

I cycled Mobile > Files OF > ON. No change.

System

iPhone 12 Pro

iOS 18.3.1

Model MGMN3X/A