How can I dynamically change the NetDriver?

Yes I have found it. You do not need to change the net driver. Now I did some modifications in DefaultEngine.ini (AndroidEngine.ini if needed for android)

Disabling NAT forces EOS to use direct connections between Players. Not trough EOS servers. Find [OnlineSubsystem] tag then add bIsUsingNAT=false line. Do this, then restart the engine.

[OnlineSubsystem]
bIsUsingNAT=false;

Let me know if that works.