I hate writing code when there are ready made UDFs that can do it just as well. Go get yourself ArrayEnumKey() and ArrayEnumValue() and give this a shot. It doesn't do anything more than enum and display all the values but should give you an idea of nesting loops.

I don't suggest this is the best way, it is just an example. I would probably use AScan() to look for the specific value.
Code:
Break On
Dim $BaseKey, $Key, $Value
$BaseKey = 'HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\Interfaces'
For each $Key in ArrayEnumKey($BaseKey)
  For each $Value in ArrayEnumValue($BaseKey+'\'+$Key)
   'Value ['+$Value+'] in Key ['+$Key+']' ?
  Next
Next
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