403 error after loading a page with many images

I’m managing a website that has a page with over 200 images (gallery).

When I open this page, and after loading the images, updating the page or opening another page on the website, I get the error 403: Acesso to this resource on the server is denied!”, and I am unable to access the site for a while.

The problem is with Cloudflare, if I remove or put Cloudflare on pause, the error does not occur.

I don’t have another CDN and Hotlink protection is off. I’ve already lowered Cloudflare’s security level and tried dozens of other configurations. But with Cloudflare ON, the error always happens after loading the page.

I don’t know if it helps but in the browser programmer tool it says the following:

report-to: {“endpoints”:[{“url”:“https://a.nel.Cloudflare.com/report/v3?s=mNncBydKMCLyZ1eR9hOALTNo7gCVINYfky%2FqoEsSamWEqdcJXFp4b5VaMD%2FGOo1sxjfgBBihTH7QVUC5VNXjkjgGHt9%2BvGh8ufLH8xVA5HGCS4JE1GHVYgoQytQ%3D”}],“group”:“cf-nel”,“max_age”:604800}

Is there any configuration I can do on Cloudflare to resolve the issue? Or will a page with that number of images always cause problems with Cloudflare?