Nikon Z9 Mirrorless Camera - Manual (Page 440)

440 Radio AWL
2
C : Select [Radio AWL] for [Flash
control] > [Wireless flash options] in the
photo shooting menu.
3
C : Choose a channel for the WR-R11a/
WR-R10.
Set the WR-R11a/WR-R10 channel selector
to the desired channel.