Calculate the confidence interval of a population mean using fitlm

Hi Matlab buddies,I would like to calculate the confidence interval of a population mean using fitlm. My code is now the following:

F_reg=filloutliers(F,'nearest','median');

mdl= fitlm(T(Index,3),(F_reg));

coefCI(mdl)

and my response from matlab is:

ans =

26.0786 26.6921

-0.8602 -0.7681

P.S. I am generating my confidence interval from the plot below.

Thank you you in advance