This release fixes bugs in 3.3beta1. See https://github.com/Duet3D/RepRapFirmware/wiki/Changelog-RRF-3.x-Beta-&-RC#reprapfirmware-33rc1 for the change list and upgrade notes.
The IAP files and file DuetWiFiServer.bin are unchanged since 3.3beta3.
Users running Duet with attached Single Board Computer should upgrade from the unstable package server feed. Users running Duet in standalone mode can use the files here.