When I push the preflight button in the DPS 2015 web interface the preflight progress starts, but it stops after a little more than 50% of the progress. After nothing happens for ages (>1 hour) the blue bar turns red and the message "preflight failed because of a network error" is displayed (see screenshot). If I retry the problem occurs again...
I get this Preflight red bar all the time, and also VERY slow preflight updates. Either watching the blue bar crawl across, or waiting for the recent update to hit the preflight app I've created. Network here is 125.53mbps. ie: fast.
This happens to me sometimes, I get the red bar after preflighting -- but in almost every case the preflight has worked. So I typically ignore the red bar and keep working.
When I return to the Portal later, preflight works just fine and I don't get the red bar.
(I think I recently triggered the red bar by clicking the preflight button when I was in a collection (changing article order) and before the preflight was done I left went Back to a higher level. I got a red bar then, but preflight worked fine.)