Some API request failing through cloudflare and nginx proxy manager

I'm hoping someone can point me in the right direction.

I have a fqdn and have a tunnel setup via cloudflare which goes to an nginx proxy manager which then goes to appwrite docker.

Cloudflare has WAP and ddos etc, which I think is partly my problem, but not the whole problem.

The issue i'm having is that majority of api calls are rejected when there's thousands of promises. if I bypass cloudflare and go direct to nginx proxy manager the majority will be resolved, and then if I bypass both cloudflare andproxy manager all will resolve.

Here's the error message when it fails.

status: 'rejected', reason: AppwriteException [Error]: fetch failed

Here's the split between resolved vs rejected promises depending on the route to make it a bit easier to see what I'm talking about

Route via cloudflare to nginx proxy to appwrite { okPromises: 443 } { rejectedPromises: 6277 }

Bypass cloudflare and go direct to nginx (within the lan) to appwrite { okPromises: 3944 } { rejectedPromises: 2776 }

Bypass cloudflare and nginx proxy manager and go direct to appwrite { okPromises: 6720 } { rejectedPromises: 0 }

Here's an example of the code

nodejs

let okPromises = 0;
let rejectedPromises = 0;
  const res = await Promise.allSettled(checkIfExistPromises)
    .then(results =>
      results.forEach(result => {
        if (result.status === "fulfilled") {
          okPromises++;
        }
        if (result.status === "rejected") {
          rejectedPromises++;
        }
      })
    )
    .catch(err => console.log(err.message));

Any ideas'? Thanks

Some API request failing through cloudflare and nginx proxy manager