'Windows operating system protocol 4 blocked' what it means?

Hello boys and girls,
I’ve got a little question for you ,and I am asking me to help me, please -

what does it mean if I have about 20 intrusion attempt blocked every 1 minute and they’re always similar -

Windows Operating System protocol 4 blocked

I’ve go them almost all the time. Can you tell what it means or give me a hint about where I can find some information on the topic?

Best Regards, and Thanks!