@WSW Yes, you can try as you described. The other way is that when you configuring the main Deco, you can set up the VLAN settings in the step 11. https://www.tp-link.com/support/faq/2464/

@Andrew_Z When the tablet is connected to the Deco's Wi-Fi, what's the IP address on the tablet? Can it ping the Deco's LAN IP, www.google.com, and 8.8.8.8 successfully? When the tablet connected to...

@Marco68 For your problem, you can refer to the link below to have a try. https://www.tp-link.com/support/faq/2718/

@Andrew_Z It seems your Samsung Galaxy Tab 4's Android version is very old, is it possible to update your OS version and then check if it will work better?

@strasznyspamer Currently, all of the Deco products can only be configured via the Deco app, can't be configured via the web UI. Good day.

@WSW The VLAN ID & priority are provided by your ISP, if you don't have the information, it's suggested to contact your ISP.