Here’s the figure.The thin ring is the conducting spherical shell. Now, for all Gaussian surfaces of radius less than R, the enclosed charge is Q only. So, shall we have a non-zero electric field at those points? Doesn’t electric field have to be 0 everywhere in the region enclosed by a conductor?
This second figure shows one such Gaussian surface I am talking about.
The blue line indicates the Gaussian surface. Will the electric field at points on the circumference of the blue Gaussian surface be 0 or non-zero?