If the long nails stop water from reaching to any part of the hand which must be washed in Wudhu, it will then cause the Wudhu to be invalid. But if you ae sure that water is reaching to every part of your hand which must be washed in Wudhu, then you have no problem.
It is better to avoid long nails as it can cause some times preventing water from reaching and if such thing happens, the Wudhu will be invalid.
Wassalam.