Question about network failure 3 and 5

Hello. I have watched some videos and tried to build sessions through LAN.

This is the video I mainly focus on:
I have inserted two lines in the DefaultEngine.ini:

But when my server hosts a game, the client comes out network error with failure type 3 and 5, which are “Connection Lost” and “Failure Received”. It is the same case when I run the tutorial project of the video. But my friend run the tutorial project without failure. Is my networking setting of my notebook wrong? Has anyone got the same problem? How to solve “Connection Lost” and “Failure Received”?