Do guests need internet at the venue?

Yes, to upload: the page runs in the browser and each photo goes from the phone to the gallery over the guest's mobile data or the venue's Wi-Fi, so a venue with no signal at all means uploading later rather than on the spot.

Later is fine. The QR code, the event code and the link keep working until the event expires, so a guest who had no signal in the cellar bar can upload from the taxi, from home or the next morning. Put the Wi-Fi name and password on the same sign as the QR code if the venue has a network.

A weak signal is usually enough. The page itself is small, the gallery loads thumbnails rather than full photos, and an upload that is interrupted is retried a few times, waiting for the connection to come back before it tries again.

What the page does not do is store photos to send later: an upload needs a connection while it runs, and if it cannot complete, the guest picks the photo again once there is signal.