I have this hardware arrangement. FPP v5.1 on Raspberry PI 4 using DDP (raw) for two F16v3's.

Everything works. First display is perfect. Second display is muddied up a bit. FPP is setup for two IP addresses, 8 universes per IP, proper START channel on both F16v3s.

Vixen is creating the v2.6 FSEQ - since display 1 is ok, Vixen is good.

It looks like the colors are off by one channel as both do a color wash.

These mirrored displays are exactly that. Mirrored. Identical.

What could be causing display #2 to get bad data?

NOTE: For ease of setup, here is the network route: FPP to display #1 network port. Display #1 network port #2 to network switch. Network switch to display #2 *AND* local LAN to facilitate controller access.