Is it obligatory to repeat the Fajr prayers that were performed after an Adhan that is most likely to have been called before the true dawn (Al-Fajr Al-Sadiq)?

The Fajr prayer, or any other obligatory prayer, must be repeated if it was performed before its due time, because the entry of the time is a condition for the prayer's validity. This applies if the dominant presumption was based on a thorough investigation and observation by someone familiar with the শরعي (Shari'ah) signs. However, if it was based on obsessive doubts and suspicions, then it does not need to be repeated.