Although I find this method infinitely ugly, I found it online and it might be working in your case:
https://www.robertkehoe.com/2013/01/fix-for-phonegap-connection-to-server-was-unsuccessful/
However, I really hope we can find a cleaner solution to this problem.
And on top of it, I would love an explanation why it happened to me in a production app that was working fine for weeks.