Questions concerning add content via Web App

Q1) When adding content via the Web app (The Desktop App on Mac is once againg not working since last update and WD seems to gave up on it) it does not upload Files approx. 3,5GB in size. Any ideas why? The manual says up to 5 GB is fine. It starts to upload but will stop after a while.
Q2) When I about to upload a file, and it already exists in the same folder the my cloud home does not tell me so. Is there a way I will be informed that I am about to upload a file twice?

Hello ctr207,

If the data transfer is taking longer time than expected than you could try to transfer files in parts instead of all the files as the device would become slow over the internet.