Thank you for your answer, I have solved this problem by changing the IP addresses of my PC.
But it is weird that the IP addresses in the file /config/etc/network/interfaces from the SD card is, for example, 192.168.0.102, but in the “Internet Protocol Version 4 (TCP/IPv4) Properties” window, I have to enter 192.168.0.101 as the “IP address”.
Anyway, I can use the rt box web interface now, and thank you again.