بسم الله الرحمن الرحيم
If something happens that breaks wudhu at the time of making wudhu, for example passing wind, then it is mandatory to make wudhu afresh. If one washed one’s hands and passed wind then the previous act got annulled, thus he should start his wudhu again.
Allah knows Best!
Darul Uloom Deoband
This answer was collected from the official ifta website of Darul Uloom Deoband in India.