Multiple nested IF VLOOKUPs

I would list sheet name in C1:H1
B2
=INDEX(2:2,MOD(MAX(INDEX(LEN(C2:H2)*100+COLUMN(C2:H2),)),100))
C2:H2
=VLOOKUP($A2,INDIRECT("'"&C$1&"'!a:b"),2,)&""

Perhaps a tidier way:

With a list of sheets in F1:F6:

This array formula in C2, copied down:

=IF(A2="","",IFERROR(VLOOKUP($A2,INDIRECT("'"&INDEX($F$1:$F$6,MATCH(1,--(COUNTIFS(INDIRECT("'"&$F$1:$F$6&"'!A2:A100"),$A2,INDIRECT("'"&$F$1:$F$6&"'!B2:B100"),"<>No IP")>0),0))&"'!A$2:B$100"),2,FALSE),"No IP"))

Array Formulae are a little different from ordinary formulae in that they MUST be confirmed in the FIRST CELL ONLY by pressing CTRL+SHIFT+ENTER to activate the array, not just ENTER. After that, the array can be dragged down as normal, to cover the desired range.

You will know the array is active when you see curly brackets { } - or "curly braces" for those of you in the USA, or "flower brackets" for those of you in India - appear around the outside of your formula. If you do not use CTRL+SHIFT+ENTER you will (almost always) get an error message or an incorrect answer. Press F2 on that cell and try again.

Don't type the curly brackets yourself - it won't work...

3D searches (multiple sheets) won't work the way you were going about it. The formula makes a 3D array of your 6 sheets and a) looks in A2:A100 for the Server name and b) in B2:b100 for anything that is not "No IP". It returns an array of 0s (no match found for both conditions and a 1 for the sheet matching both conditions. So, in cell C2, it returns (0,0,0,0,0,1) This tells Excel to look in the 6th of the sheets in the list of sheets (.ty) and do the VLOOKUP on that sheet.