There are a few things you can try to troubleshoot the issue with slow VPN connection to FTDv with FDM management:
Verify the network connectivity between the AnyConnect client and FTDv with FDM management. Make sure that there is no network latency or packet loss that can affect the connection speed.
Check the AnyConnect version compatibility with FTDv 7.2.3. Make sure that the AnyConnect version you are using is compatible with FTDv 7.2.3. You can check the compatibility matrix on Cisco's website.
Check the FTDv configuration for AnyConnect. Make sure that the AnyConnect configuration is correct and the necessary policies are applied.
Enable debug logging on the FTDv with FDM management to check for any errors or issues that might be causing the slow VPN connection.
Try upgrading the FTDv with FDM management to the latest version to see if it resolves the issue.
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