Testflight testers getting “unable to download app could not be installed at this time”

Question

I distributed version 1.0, build 1, of my app via TestFlight, and everything worked perfectly.

Yesterday I archived and sent out build 2, and now upon tapping the upd

Answer 1

Encountered exactly the same problem today, trying to install a new testflight version downloading it through our company WiFi. We noticed that we could still download and install the app from mobile devices through LTE which lead us to the conclusion that for whatever reason testflight must have blocked our office IP (temporarily) for unknown reasons.