Do not work XDMCP GDM3

[Konstantin <koc32@mail.ru>]

Dear Maintainer,


I'm setting up a server for multi-user use.
For this I use XDMCP, GDM3, xinetd, TightVNC
I changed the settings of /etc/gdm3/daemon.conf to:
[daemon]

[security]
DisallowTCP=false

[xdmcp]
Enable=true
MaxPending=4
MaxSessions=16
MaxWait=30
MaxWaitIndirect=30
PingIntervalSeconds=60
MaxPendingIndirect=4
DisplaysPerHost=2
HonorIndirect=true
Port=177

[greeter]

[debug]
  Enable = true

Settings for /etc/xinetd.d/vnc:
service vnc
{
   disable     = no
   socket_type = stream
   protocol    = tcp
   wait        = no
   user        = root
   server      = /usr/bin/Xvnc
   server_args = -inetd -once -query localhost -geometry 1024x768 -depth
16
   type        = UNLISTED
   port 
}

Settings for  /etc/xinetd.conf:
defaults
{
log_type = SYSLOG daemon info
log_on_success  = HOST PID USERID
log_on_failure  = HOST USERID
cps             = 200 5
}

Added to / etc / services:
vnc             5900/tcp                        #vncserver

But after all the changes, when connected through the client, only the
gray screen appears.
Made the configuration for a specific user .vnc / xstartup:
#!/bin/sh

xrdb $HOME/.Xresources
xsetroot -solid grey
#x-terminal-emulator -geometry 80x24+10+10 -ls -title "$VNCDESKTOP
Desktop" &
#x-window-manager &
# Fix to make GNOME work
export XKL_XMODMAP_DISABLE=1
gnome-terminal &
mutter
/etc/X11/Xsession

When connected to an active user, everything works fine.

I need to, when connecting to a remote session, a window manager is
loaded where it is possible to select a user. When using Ligthdm this
happens, but I would like to use GDM3.