Here comes the update
I tried to restart the tftp whcih @Tom Elliott mentioned below.
I did edit my dhcp config just the exactly the same as @Wayne-Workman 's reply below.
And I also add one more line refer from @Uncle-Frank 's reply below.
I tried those methods separately, but didn’t work out well.
However, when I combine those methods together. Fog server finally run and I can upload and download images to the machine now.
Thank you everyone who contributes in this post.
Note: there is a login fail problem with this particular setting. To resolve this issue, change your password through the database to modify your password.