Assistance with Unique values using a formula

Assistance with counting a unique number.

Col A is for IP Address
Col B is for severity (Low Medium High Critical))

I have the following code:
=SUM(IF(
({"Low","Medium","High","Critical"}=DataSheet!$B$1:$B$100),
1/COUNTIFS(
DataSheet!$A$1:$A$100,DataSheet!$A$1:$A$100,
DataSheet!$B$1:$B$100,{"Low","Medium","High","Critical"}
)),0)

This is searching column B for {"Low","Medium","High","Critical"} (not info) and returning with 14 unique IP Addresses from column A as the result which is incorrect. It should be 5 unique IP addresses.

When doing each severity at a time, it works. See below:

Low - 3 unique IP addresses
Medium - 3 unique IP addresses
High - 4 unique IP addresses
Critical - 4 unique IP addresses

But, when I do total, it returns with 14 because its just counting the total from each severity

The issue is, I only have 5 IP addresses total so the answer cant be 14. As a whole, this should return as 5 unique IP addresses.

I have attached an example worksheet.
Thank you.

HELP Please, I'm stuck!

Try this in B7:

=SUMPRODUCT(1/COUNTIF(DataSheet!$A$1:$A$50,DataSheet!$A$1:$A$50))

It works but column B has 5 different things (Low, Medium, High, Critical, Info).
I need it to not count INFO so thats where I'm stuck, This current code will count the infos.
Dave

Anyone? I'm at a loss

XOR LX it works. I don't know how you did it but I've been struggling with this for hours.

Out of curiosity, How would I add one more criteria into this formula?

So using the same info as before but say Column C had three different manufacturers in it like "Apple" "Windows" "Linux"
And I wanted to start this code off by saying if contains Apple or Windows, then proceed with this code?
So it would index column C somehow to verify the criteria is met before proceeding?

Thanks

Thank you very much! I would have never figured this one out. Your understanding of excel is Amazing. Thank you!