I don't know why I feel confident when I talk one on one, but when I am in a group or more than 3 people I feel awkward?

When i talk with person one on one i feel confident, but when i am with 3-4 or more people i feel weird, awkward and shy or not know how to communicate. I don't know how to change it and why i feel this way even with people i know.

I don't know why I feel confident when I talk one on one, but when I am in a group or more than 3 people I feel awkward?
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