Thanks for the response; yes that was a typo (the real project name is “ProjectDev”).
In fact, that is my post that you referenced 
Thanks for the link to the bug reports! I’ll post back here if I make any progress.
Here’s what worked for me: in your Config/DefaultEngine.ini file, make sure to have
[OnlineSubsystem]
DefaultPlatformService=NULL
Do the same in Config/IOS/IOSEngine.ini (make it if it doesn’t exist). Adding this allowed me to join a multiplayer game from iOS