File upload field cutting file size and file content

[a-ok]

If I'm uploading a .mp4 (could potentially be any file) to a file upload field and the file is 3mb but on uploading the file is 600kb and then the .mp4 is glitchy/plays for only a few seconds (in the browser) is it safe to assume something wrong is set on the server? I've never had this issue before (use DigitalOcean, mainly) but I'm using LCN for a client and this issue has only just occurred since migrating from my dev to LCN.

Any thoughts?

[a-ok]

I've attached some images. I'm assuming it's an LCN server issue but they've stated they don't limit/cap anything. Same file on localhost and a DigitalOcean server upload fine whereas on LCN it jumps to 600kb and effectively breaks the file.