worked with Play 2.3, now seems to fail with Play 2.5

[gknauth]

A year ago (2016) I used this plugin very successfully with Play 2.3, to deploy / run apps on AWS/EBS. I've since moved to Play 2.5, and now, using this plugin (and trying other plugins too), I can deploy to AWS/EBS but not run anymore. I get a Gateway 502 error on the webapp's main page, and in the nginx logs I see: connect() failed (113: No route to host) while connecting to upstream and I have no idea where to go from here. All I know is everything used to work fine, and now it almost does but doesn't. I put a question on StackOverflow last week and nobody seems to have an answer. Should I not be using Play 2.5? Should I not be using any kind of Docker plugin? Should I not be using AWS/EBS? Does sbt-elastic-beanstalk still generally work for people, or are there better things now? I'm just kind of lost at this point, and unfortunately it's something I have to figure out sooner rather than later.