Set up xdmcp for remote desktop forcing udp v4

I am trying to set up remote desktop into a Debian stretch distribution, I set up the file /etc/gdm3/daemon.conf. [daemon] WaylandEnable = false [security] DisallowTCP = false [xdmcp] Enable = true Port = 177 [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 But when I restart the debian system, I see the following output on netstat: udp6 0 0 :::177 :::* 11059/gdm3 That is using udp6 and not udp4. I have tried disabling inet6 into the system with the following lines into /etc/sysctl.conf: net.ipv6.conf.all.disable_ipv6 = 1 net.ipv6.conf.default.disable_ipv6 = 1 net.ipv6.conf.lo.disable_ipv6 = 1 I refresh the settings with sysctl -p, and restart the services with sudo init 3; sudo unit 5, but nothing change. I have rebooted the VM even, and still the same. Any idea how I can force xdcmp to be listening on UDP v4 and not udp6?? Thanks in advance. I am doing this to figure out the settings needed into another machine with the same linux distribution where I want to set up remote access to the desktop (so, I am gonna get the same issue). Actually I can access with xvnc running into the other host, but I want to set up xdmcp to request the login on remote access. The exact system I am running: $ lsb_release -a No LSB modules are available. Distributor ID: Debian Description: Debian GNU/Linux 9.4 (stretch) Release: 9.4 Codename: stretch $ apt-cache show gdm3 Package: gdm3 Version: 3.22.3-3+deb9u1 . . .