If the scenario is occurring, the following may be true regarding Experience Site Login Session Settings:
Option 1: Disable Separate Experience Cloud site and Salesforce login authentication for employees and establish a new login session. The steps for this are:
Option 3: Disable the following Session Settings: Lock sessions to the IP address from which they originated, Lock sessions to the domain in which they were first used, Enforce login IP ranges on every request. The steps for this are:
Please note: These settings are only available in Enterprise, Performance, Unlimited and Developer Editions organizations. If your organization is not among these, then you will not have access to this setting.
Salesforce Help - Modify Session Security Settings
000383785

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