I have a 4 tb wd my cloud and with the new version mycloud 5.0 I can’t upload file larger than 5 gb.
Are you using the web app to upload a file larger than 5GB? If so there is a 5 GB limit. See the following WD Knowledge Base Article for more information and suggested workarounds.
My Cloud OS 5: Error Uploading Large Files in Web App
Files larger than 5 GB cannot be uploaded using the My Cloud OS 5 web app.
This 5GB file upload limit is an issue well complained about in a number of past discussions. One can use the forum search feature, magnifying glass icon top right, to find those past discussions.