You can check the referrer information by accessing the 'Teachme Biz Environment Diagnosis Page' on your web browser or mobile browser.
If the referrer (source) restriction function is not working as intended, please check the referrer information by referring to the link.
Related: Check Referrer Information (Web Browser Version)
https://teachme.jp/8/manuals/42393733
When the referrer information is displayed
Please allow the part or all of the URL displayed on the diagnosis page as the referrer (source).
*The referrer information is partially matched against the string registered as the referrer (source) URL.
Related: Restrict access with a specific referrer URL or password (Web Browser)
https://teachme.jp/8/manuals/10033436
When the referrer information is not displayed
In some cases, the referrer information may not be retained depending on the environment of the allowed referrer (source) page.
If the referrer information cannot be confirmed, the referrer (source) restriction function cannot be used.
Please consider either of the following options:
Modify the referrer (source) page to send the referrer information
It may be possible to resolve the issue by implementing the 'meta referrer' tag, which can specify the transmission of the referrer when clicking on a link and transitioning to another page.
For details on tag implementation, please check with the provider of the allowed referrer (source) page.
Apply access restriction other than referrer restriction
For the public folder, access can also be restricted by 'Password' in addition to the referrer.
Related: Restrict access to the public folder by referrer URL or password (Web browser version)
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Related: What is the referrer (source) function?
https://help.teachme.jp/hc/en-us/articles/900005510846