@phad I am reluctant to offer anything related to Deco mesh configuration. This is what you can do: 1. Connect laptop to free Ethernet port of "the box." Verify laptop has Ethernet link and not using...

Chunmeng wrote @Alexandre. i am currently using D link DIR-842 C2 with WiFi speed package of 500mbps @Chunmeng This appears to be standard WiFi 5 capable router. It maybe time to replace it with WiFi...

@phad Also, after you've done manual reset of each Deco unit, you may need to delete Deco mesh network itself, here is how: How to delete a network on the Deco app Follow Scenario 1. After that, you...

@phad Follow this FAQ: How can I reset or reboot my Deco Whole-Home Wi-Fi System?

@Chunmeng What do you have as your router now: brand, model name?

@phad Apologies, this is not expected outcome. With ISP Router it is supposed to work, and you did all tests for me to verify "the box" is router. If you didn't do that yet, power off both "the box"...