update..

roles/common/tasks/ubuntu-x11vnc-1804-amd64.yml

@@ -24,6 +24,21 @@
     shell: echo "$(id -u gdm)"
     register: grp_id_gdm
 
+  - name: Check if file '/etc/gdm3/custom.conf' exists
+    stat:
+      path: /etc/gdm3/custom.conf
+    register: etc_gdm_custom_conf_exists
+
+  - name: Adjust file '/etc/gdm3/custom.conf'
+    lineinfile:
+      dest: /etc/gdm3/custom.conf
+      state: present
+      regexp: '^WaylandEnable'
+      line: 'WaylandEnable=false'
+      insertafter: '^#?\s*WaylandEnable'
+    when:
+      - etc_gdm_custom_conf_exists.stat.exists
+
   - name: "(ubuntu-x11vnc-1804-amd64.yml) Store password"
     raw: "x11vnc -storepasswd {{ vnc_password }} /etc/x11vnc.pass"