(FSSO) Multi ad logins with the single IP

Current Setup:

We are using Explicit Proxy on FortiGate with FSSO-based user authentication.

Challenges Faced:

Scenario 1:

We are using N-Computing devices, where multiple users log in simultaneously. These users all share the same IP address.
As a result, we are facing the following issues:

• Some users are intermittently unable to access the internet.

• In certain cases, user traffic is incorrectly attributed, leading to policy enforcement mismatches and access issues.

Scenario 2:

We have scenarios where a single user account is logged in on multiple devices simultaneously.
This allows the user to access the internet from multiple devices at the same time, which is affecting the reliability and accuracy of user-based controls.

Is there any solution to over come the above issue.