Allow the following as a whitelist
Also, please open ports (80, 443) for outbound communications and responses.
*1: IP addresses of "teachme.jp" and "*.cloudfront.net" are not disclosed because they change irregularly.
*2: If the network is used only by browsing users, the communication permission described in 4-5 above is not required.
However, if the permission is changed from the browsing user to the editing user, the communication permission of 4-5 is required.