Agent Scan on timeout

Agent Scan on timeout

Good morning,
I have this persistent problem. Any scan from agent results in this message:
"OPTION FAILED: The scan request has been received and acknowledged by the agent. The agent is taking longer than usual to complete the process. The scan data will be updated once received. Try again later."

Do you know what the problem could be?
I have tried various workstations between mac and pc all with agent updated to the latest version.
The Service Desk Plus build number is 14820.
The Endpoint Central build number is 11.3.2428.10 .
The agents are at version 11.3.2428.10.W .

Thanks a lot in advance.

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