If you want to find the cause , you need to trace network traffic and monitor the requests coming from which port. Tool such as Network Monitor and Process Monitor can be considered . However, analysis of log is beyond our forum support level and due to forum security policy, we have no such channel to collect user log information. You may need to analyze by yourself.
Please refer to the following video, see if this can help with you:
lsass.exe high network traffic from the internet FIX! server 2012 r2
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