Error when uploading big file, small files fine

[haydena]

Hi all, i am getting a error when i upload a big file to my resource manager. I have checked all php settings and theyre not the issue. I did read somewhere it is to do with mod_security but my control panel for my VPS does not use this. I am not to sure what to do can you please advise.
Screenshots attached.
Smaller files upload fine.
I am using Cloudflare as my CDN but dont have any conflicting rules.

Error from console:
"Mixed Content: The page at...

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Error when uploading big file, small files fine

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