Starting from Magento 2.4.4 integration tokens can no longer be used for API Bearer token authentication. This behavior has been disabled by default due to the security implications of a never-expiring access token. To enable it go to Configuration > Services > Oauth and set Allow OAuth Access Tokens to be used as standalone Bearer tokens to 'Yes'.
For using Langshop application your environment has to be visible externally, that’s the common requirement for allowing communication between application and Magento extension.
By cases, if your instance is not accessible outside, such as basic auth or restriction by IPs enabled, reliable work of application can not be guaranteed.
The website must have an active SSL certificate for the application to work.
Which IP address(es) is the extension trying to communicate to?
IP 18.104.22.168 must be whitelisted