Firstly I tried to install multi site into sub-directory.

At that time, I had problem with port because its not 80. But thanks to this article Cannot install a network of sites – WordPress and XAMPP
, I solved it.

So now, I tried to add WordPress multi site in My Sites section of admin screen, but port number is not reflected in URL as below (2nd URL also should be loclahost:800)

Even if I edit andreplace this URL with localhost:800, it was saved as localhost automatically. (I think I need to modify some specifi PHP file)

Please someone tell me how to add :800 in 2nd URL too.