What Howard said!!! You've not answered the question but stated that via some tool you've used to check, has reported X. But, here again ... if resources are not the issue, then, as Howard says from time to time ... 'prove it'.
Moodle is an app ... it's not the operating system. It does NOT have any setting to 'control' networking. It might have settings that need tweaking for better performance related to the code. There is also DB server (we know nothing about that) and the web service in front of it all.
Devils are always in the details ... and sometimes ... in places 'we' (including you) didn't think about checking.
'SoS', Ken