UE4 blueprint multiplayer tutorial issue/question

Hi Guys
I am following the UE4 blueprint multiplayer tutorial and everything was running well till I tested at the end of slide 16 - player card setup.
Instead of my host server starting a game that the client can join, it starts a game and the client is automatically joined without having to search for the game (as per the tutorial)

This is the tutorial:

https://docs.unrealengine.com/en-us/Videos//PLZlv_N0_O1gYqSlbGQVKsRg6fpxWndZqZ/_-yal2ufWP8

Any ideas on what could be going wrong?

Thanks

Stephen