@arbazparacha 

Hi, is your Deco X20 in Access Point mode?

Can I have your current network diagram/topology? Would there be a network switch used for the Ethernet Backhaul?

By the way, did you use any customized firewall system, like Pi-Hole to filter the DNS query?

I thought Deco online detection packets might be blocked in the network.

Wait for your reply and best regards.

  @mojohoojo 

Hi, could you please refer to this link to help me submit the APP log:

How to submit Deco APP log

"I can't save setting and unable to assign bandwidth to persist 5G", Do you refer to the "connection preference" feature on the APP?

Would there be any error message?

If possible, could you please save a video clip of how the Deco APP behaves?

And " also unable to see devices connected to decos", is the online list blank?

Thank you very much and best regards.