I used Xiaomi Mi 3, that the MIUI default file browser has a feature, which allows FTP server setup. So that you can access the phone’s storage through the FTP server, without USB cable. As long as your computer and your phone is using a same LAN.

But since my Xiaomi phone is rest in peace, I bought Huawei phone. And the Huawei phone doesn’t have this feature. So, looking around from Google Play store, I found the FTPServer. It is nice to setup, including username, password, port, and the default directory. (Note: please set the default directory to the SDCard, others are inaccessible.)