@Data_RS Have you considered reverting your firmware to an earlier version to determine if that resolves the issue? You can find the necessary steps in the post linked below....

Ethernet backhaul If you are experiencing difficulties with setting up Ethernet backhaul or configuring your network switch with your Deco device, we recommend consulting the following links for...

@Libertesa Please ensure that you have your Deco and switch configured using either Option #1 or Option #2 as outlined in the article below: https://www.tp-link.com/us/support/faq/1794/ If you...

@Dcap Is there a switch at all in your network? If so what brand and model?

@Graycase There is a web based option but it's very limited http://tplinkdeco.net/

@Ryan That must be an option not all Deco's have? I don't see it in the options for my XX75 pro