No, an online waiting list ticket that remains unconfirmed (WL) after the chart is prepared is not valid for travel in reserved coaches (AC or Sleeper). As of May 1, 2025, Indian Railways has implemented strict new rules prohibiting waitlisted passengers from boarding reserved compartments to reduce overcrowding. If your online ticket is still on the waiting list, it will be automatically cancelled by the system, and a refund will be issued to your account. Attempting to travel in a reserved coach with such a ticket will result in being deboarded by the TTE and facing penalties: ₹250 for Sleeper Class and ₹440 for AC Class, plus the fare to the next station. You may only use a waitlisted ticket to travel in General (Unreserved) coaches if you have obtained a physical ticket from a station counter, but online "e-tickets" that do not confirm are strictly invalid for travel and won't even be accepted by the TTE.