Ask your hoster where are your logs.
Sorry, but we can't help you without the log.
In your log, I see a lot of 503 error, meaning the server is peharps overloaded, or there is restrictions on it.
Peharps a security_mod or just a poor hosting limiting http queries.
I recently asked them to increase memory in php.ini and they have .. Still having issue.. It's so annoying xD
It's not PHP, it's apache or nginx. The server stop answering, or didn't answers to certain queries.
It's weird that it only happens on that specific module "reports" xD