For the DefaultEngine.ini file, it’s mostly a trial and error thing. If you do a search within this forum or Google, you’ll see there’s not a lot of things there.
For Steam and Oculus Home it’s straigthforward (see precedent post)
OnlineSubSystemUtils contains the basic functionalities of networking, so if it doesn’t find Steam it will naturally fallback to this.
I’ve tested IPDirect, LAN and dedicated server with null subsystem just to be sure to not use Steam if it’s still open somewhere
That’s true the VOIP through DirectIP is halfway done and needs customization to your project, that’s why I left it like this.
As I did not have any paid project demanding this we (as a company) dit not pursue more in that field; however I should have a project requiring it soon so I’ll give soon more complete guidance on this!