@yves_b Not sure if you solved your printer problem but if you haven't you may want to try the following: Change your DECO from a WIFI Router to an Access point.
The setting can be found by using the phone app at the bottom of the app ( I am using an Iphone) You will see "MORE" click on that . Select "Advanced" At the top it will say "Operation Mode " By defult "WiFi Router" is selected. Change the setting to "Access Point" System will reboot about 2 to 3 minutes. Try your print and scanning and see if you now have connectivity. This worked for me for a older ethernet cable connected Brother printer that has no WIFI built into the printer. This printer had worked on a previous wifi access point system for the house before I installed the new DECO mesh system. Hope that helps.