and I wanted to update you on the status of my problem. As you can see from the pictures below the design of the coupling between the pin and flange on the shaft has changed a lot.

As you can see from the figures below, following the advice of I further simplified the model by replacing the point mass that represented the CG of the WP (and on which the force of gravity was acting), with a moment and a force concentrated on the flange. All the other settings are the same.
However, going to solve the model, I noticed a possible inconsistency. The total reaction of the moment evaluated to the fixed support is 1500 Nm, exactly like the moment I applied to the flange; on the other hand, the total reaction force is much less than the 5000 N applied by me. In your opinion, what could be the reason for this discrepancy?

In addition, I would like to ask you if you think it is appropriate to improve the mesh and, if so, what strategy I could adopt to achieve the purpose

Thanks to both of you for your kind help