This is the first release of the 3.4.0beta series. See https://github.com/Duet3D/RepRapFirmware/wiki/Changelog-RRF-3.x-Beta-&-RC#reprapfirmware-340beta1 for the change list and upgrade notes. Note, this release does not support input shaping.
Users of Duet with attached single board computer should upgrade to this release from the unstable feed on the package server. Users of Duet in standalone mode can use the files here.
File DuetWiFiServer.bin has not changed since release 3.3 so it is not included here.