I have a known good web page that works without (known) errors when it loads. However, when I try to load it using a very laggy connection (more than 6-10 seconds to load the page - when all works well, it can load in under 500 ms), my hosting provider seems to generate 503 (too many requests) messages, and of course loading fails.
The page uses several modules I've written, and uses an asynchronous loader to read them once, when they're needed, so a single page load will often generate 10-20 GET requests for assorted resources. (Actually, it's closer to 60, but the rest come from a Google CDN, without error).
The hosting provider doesn't seem to understand (or, perhaps, care) about this problem, of course. I'm curious, though: does this sound like something that could be automatically generated by Apache (e.g. using mod_security or mod_cband), and would this be something that didn't show up on the log? I am very much a novice with Apache config, but find this error is forcing me to learn it.