How to capture network traffic during computer bootup

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Hi,
I would like to perform netcap to capture traffic during my computer bootup.
I tried to do it via Group Policy but does not seems to be working. The
reason i want to do this is because i can see from userenv log, GPO is taking
more than 5 minutes to complete but not sure what kind of traffic is running.

Any idea how to do this?

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