Odd html caching issue?

WO 5.2.3, OSXS 10.3.4 on all hosts,
Webserver is also an appserver, with another dedicated app server, Monitor
running on dedicated appserver.

After moving our servers to a new subnet, one of our apps started logging
lot's of broken pipe exceptions.  The end user result were lots of "No
instance available" messages.  So, after finally getting a response page
back by connecting directly to the instance running on the webserver, I
noticed that there were a lot of invalid links.  They are all links that
reference resources located on another server, so they're of the form
"http://server.domain.com/path/to/the/resource.jpg", etc.  I thought,
"Great, I can just edit these static refs directly on the deployed
components source and fix it all".  Wrong, the html source on the component
has these referenced correctly.  So, it looks like apache is vending an
older version of the html associated with the component in question.  I
don't have performance cache enabled on the server.  So, my questions are:

How is this possible?  Where else would the html be coming from?

Why did it just start happening now?

Being that these links are static references to resources outside of the
app, why does this affect WO at all?  I would think that if apache can't
find a resource, it would just vend the page with the broken links and WO
wouldn't give a damn either.

Thanks for any insight; I'm going to try just killing everything and
rebuilding as I need to get this back up pretty quick.
-- 
William Hatch
Eng. Visual Media Collection
Cornell Lab of Ornithology
Macaulay Library
Voice (607) 254-2116
Fax (607) 254-2439