Export Display is not working on Ubuntu Gnome (gmd3)

Question

When I try to export the remote display I do:

In my Ubuntu 17.04:

xhost +
access control disabled, clients can connect from any host

Then I make the connection to the server:

ssh user@server

Once in the server get this error:

user@server:~$ export DISPLAY=my_ip:0.0
user@server:~$ xeyes
Error: Can't open display: my_ip:0.0

My gdm configuration is:

root@my_ip:/etc/gdm3# cat custom.conf

# GDM configuration storage
#
# See /usr/share/gdm/gdm.schemas for a list of available options.

[daemon]
# Uncoment the line below to force the login screen to use Xorg
#WaylandEnable=false

# Enabling automatic login
#  AutomaticLoginEnable = true
#  AutomaticLogin = user1

# Enabling timed login
#  TimedLoginEnable = true
#  TimedLogin = user1
#  TimedLoginDelay = 10

[security]
DisallowTCP=false

[xdmcp]
Enable=true
DisplaysPerHost=10 

[chooser]

[debug]
# Uncomment the line below to turn on debugging
# More verbose logs
# Additionally lets the X server dump core if it crashes
#Enable=true

GDM3 Version

gdm3 --version
GDM 3.24.0

netstat -puta

Conexiones activas de Internet (servidores y establecidos)
Proto  Recib Enviad Dirección local         Dirección remota       Estado       PID/Program name    
tcp        0      0 0.0.0.0:x11-1           0.0.0.0:*               ESCUCHAR    1477/Xorg           

ps fax | grep X

 1211 tty1     Sl+    0:01  |       \_ /usr/lib/xorg/Xorg vt1 -displayfd 3 -auth /run/user/120/gdm/Xauthority -background none -noreset -keeptty -verbose 3
 1477 tty2     Sl+    0:35          \_ /usr/lib/xorg/Xorg vt2 -displayfd 3 -auth /run/user/1000/gdm/Xauthority -listen tcp -background none -noreset -keeptty -verbose 3

tcpdump

11:41:20.065425 IP server.41874 > my_ip.x11: Flags [S], seq 1478700027, win 29200, options [mss 1460,sackOK,TS val 22197350 ecr 0,nop,wscale 7], length 0
11:41:20.065447 IP my_ip.x11 > server.41874: Flags [R.], seq 0, ack 1478700028, win 0, length 0

Solution

Solved. The problem was with my DISPLAY number. I supposed that my DISPLAY was 0.0 but :

xdpyinfo | grep display
name of display:    :1

So, the export DISPLAY must be:

export DISPLAY=my_ip:1