How were your participants supposed to access the code? By reaching the last screen of the experiment? If so, does the last screen come after the results are sent to the servers?
The whole experiment is run on the client-side, which means the servers could be down and the participants could still be running the experiment (as long as they started it when the servers were still up). But sending the results requires a functional connection, so if your screen with the confirmation code comes after that, it can’t be that the servers were down.