Step 1: Midpoint of the given points:
\[
\left(\frac{2+6}{2},\frac{3+7}{2},\frac{4+8}{2}\right)=(4,5,6)
\]
Step 2: Direction vector of the segment is \((4,4,4)\), hence normal to plane.
Step 3: Equation:
\[
4(x-4)+4(y-5)+4(z-6)=0
\Rightarrow x+y+z-15=0
\]