Hi,
I want to create a large racing game (one map dimension over 100 km), for that I need to re-base the world and use levelstreaming, also needs to have multiplayer support. I know that I wont be able to use the built in physics or netcode.
My question is, what happens to the persistent level if i re-base my origin too much? Will it teleport to the others side of the world on variable overflow?
It’s fine in the way it’s used and designed for. Obviously it won’t work for multiplayer so you have to find another situation anyway.
What do you mean by the second question? Why would you be able to do it “too much”? Unless you try to teleport instantly to different sections rapidly I think it’s fine.
As of 4.14, UE4 supports multiplayer rebasing.
Assuming objects in persistent level placed around zero origin, after rebasing origin to a point 100km away - those objects will have locations 100km away from zero origin.
What happens if i rebase it so much that even the offset vector can’t handle it? 
(I could try it out myself but I’m a bit too busy atm to set it up.)