Dear Stata Users

Comparing a RE (xtreg, re) with and IV (xtivreg, re) model, I receive quite large coefficients in the IV case. For football I have found five Instruments.
MATH Coeff. RE Coeff IV
football -0.83 -30.05
age 4.28 4.79
fear -0.62 -0.57
parentalincome 0.004 0.004
I am wondering why the coefficient of football has such a hughe difference. According to the literature I checked the IV-Model for the following conditions (xtoverid, nois).

Endogeneity: F-Test for excluded instruments F(5, 5602) = 14.8

Weak instruments: Stock-Wogo weak ID test critical values for K1=1 and L1=5: 10% max relative bias = 10.8; 5% max relative bias = 18.3

Overidentification: Sargan-Hansen statistic: p-value = 0.34

Does anyone has an idea, why the IV model seems to be strange and probabyl wrong?

Thank you very much