A little thread necromancy…
Any extra info on the required settings? I’v been trying to test 4.25 now that I’m back in the lab (what a year eh?) and from what I can tell the sync now works under DX, but I can’t get Frame Sequential steroscopic to function for UE4 at all.
For extra info, our cluster uses 28 nodes with Nvidia Quadro M6000’s, each driving 2 HD displays in mosaic (1920x2160) using quad-buffering for stereoscopic. We can run Win7 and 10, DX11/12 etc
Nvidia stereoscopic is enabled, the nvidia test app works etc, but also we’ve run our own OpenGL applications that use quad-buffering and have used Unity3D with quad-buffering. Previously nDisplay worked when OpenGL was still a part of it.
We don’t have the ability to run top-bottom/side-by-side with our cluster as that would require running a few hundred meters of extra cables and redoing our cluster, and with covid finances that’s not an option 
Is there some extra setting in UE that I’ve missed? The nDisplay documentation for Stereoscopic still mentions OpenGL etc and doesn’t say there are any additional requirements for Frame Sequential (i.e. nothing about fullscreen/windowed, any other required windows settings).
Here’s a cutdown test config I just tried using with the provided example nDisplay scene using just 2 nodes (fyi cyl14 is our nvidia sync master):
[info] version="23"
[cluster_node] id="cyl13" addr="192.168.1.113" window="wnd_cyl13"
[cluster_node] id="cyl14" addr="192.168.1.114" window="wnd_cyl14" port_cs="7777" port_ss="7778" master="true"
[window] id="wnd_cyl13" viewports="vp_cyl13" fullscreen="true" resx="1920" resy="2160"
[window] id="wnd_cyl14" viewports="vp_cyl14" fullscreen="true" resx="1920" resy="2160"
[viewport] id="vp_cyl13" x="0" y="0" width="1920" height="2160" projection="proj_cyl13" camera="camera_static"
[viewport] id="vp_cyl14" x="0" y="0" width="1920" height="2160" projection="proj_cyl14" camera="camera_static"
[projection] id="proj_cyl13" type="simple" screen="scr_cyl13"
[projection] id="proj_cyl14" type="simple" screen="scr_cyl14"
[screen] id="scr_cyl13" loc="X=2.8985,Y=-1.266,Z=2.3435" rot="P=0,Y=-24.0814,R=0" size="X=1.320968,Y=1.497" parent="cyl_origin"
[screen] id="scr_cyl14" loc="X=2.8985,Y=-1.266,Z=0.844" rot="P=0,Y=-24.0814,R=0" size="X=1.320968,Y=1.498" parent="cyl_origin"
[scene_node] id="cyl_origin" loc="X=0,Y=0,Z=0" rot="P=0,Y=0,R=0"
[scene_node] id="socket_cam" loc="X=0,Y=0,Z=1.6" rot="P=0,Y=0,R=0" parent="cyl_origin"
[camera] id="camera_static" loc="X=0,Y=0,Z=0" parent="socket_cam" eye_swap="false" eye_dist="0.064" force_offset="0"
[general] swap_sync_policy="2"
[network] cln_conn_tries_amount="10" cln_conn_retry_delay="1000" game_start_timeout="30000" barrier_wait_timeout="5000"
Any help figuring out this issue would be greatly appreciated. Quad-buffering is always causing us hassles as left-right or top-bottom would be so much simpler, but unfortunately this is the system we’re dealing with.
Oh and also…
I saw your work a few years ago Pjotr, great stuff and cheers for the quad buffering support in UE4. Now to just see if I can get it going again 