The caching period is up the the client, technically. So when we're doing template work, for instance, we'll put in a request to turn off caching altogether on our Test site. But I'm not sure what might be causing your TNEW server to keep "whitelabeling" your site. Is it possible that the template server is treating the TNEW servers differently (i.e. firewall rules, particularly adaptive firewalls) to the systems you check it from?
I didn't know turning off caching for development was an option, that's interesting. Thanks!
No problem Christian Bisgard
Something that may give us a clue is the web server logs on your end -- IIS, Apache or NGINX request logs for the host that serves your template. You should see a request for the template at least 2x within a 10 minute period, one for each host in your TNEW production array, and then if TEST is pointed at the same location, you'd see requests for that too. It would help us figure out if the request is even making it to your web hosts, or, if it is, what the error is from the origin.
Next time if it happens, check your request logs right away and see if there is an error we can use.
Thanks, support should pick it up with you from here.