Let $a_1, a_2, a_3, \dots$ be a G.P. of increasing positive numbers. Let the sum of its $6^{th}$ and $8^{th}$ terms be $2$ and the product of its $3^{rd}$ and $5^{th}$ terms be $\dfrac{1}{9}$. Then $6(a_2 + a_4)(a_4 + a_6)$ is equal to