Your server generally does not seem to like too many concurrent requests.
sitemeer.com/#https://lamyra.org/
Most checkpoints actually fail and even the ones where it works take 20+ seconds.
That’s something for your host to fix. As for the 403, you should check your server logs as well as Cloudflare’s event logs. It is either blocked on your server or by Cloudflare.
But still, you should fix these server issues.