Consider the following premises. There is at least one y_1 for which if y_1 were a server, then y_1 is sleeping. For all y_1, y_1 is a server if and only if y_1 will sleep. Can we infer the following from them? If we can, name the inference rule being used: For all y_1, if is not true that y_1 will sleep if and only if y_1 is a server.
That contradicts the premises. Therefore the answer is no.