The 'three days earlier' version of Jen bringing Josh into her apartment shows a different sequence of events from the original; originally she grabs his shirt and pulls him in after her, but in the replay she puts her arm around his waist and escorts him through the door.
Jen constantly checks for a connection at the retreat, but when the screen of her iPhone is finally seen (at 00:13:23), it's no wonder she can't connect. Everything is turned off: Cellular data, Wifi and even Bluetooth.