@Rog69 

Hi, could you please help me confirm the network map:

ISP modem router----main Deco ))—wireless or wireless?--(( 3^rd kitchen Deco

                                                          ))—wireless--((  2^nd lounge Deco------ 8 port Ethernet switch—TV/AV powerline/PC

The issue is the Ethernet connection from the lounge Deco did not work， right?

And connecting the laptop directly to the 2^nd lounge Deco bypassing the switch, still, got nothing?

After Swapping the kitchen Deco with the lounge Deco, would the kitchen Deco be able to provide any Ethernet connection or no matter which Deco is located in the lounge the same network structure failed to provide the Ethernet connection?

By the way, I guess the Decos are on the access point mode, right?

Thank you very much and wait for your reply.

@Rog69 

Thanks for your update.

Yes, the access point would be much better for your current connection since it could get rid of the double routers (NAT) issue.

But router mode should be fine,

If possible, could you please help me check the IP address and gateway when the laptop connected directly to the lounge Deco?

Then if possible, please also check the IP address and gateway on the wireless devices;

I think 2^nd Deco might confuse the switch or the laptop as the internet source, instead of extending the main Deco’s internet to the switch;

As for the different between router and access point, please refer to this link:

https://www.tp-link.com/en/support/faq/2423/

Thank you very much and wait for your reply.