Hi, Could you please provide more information about the current issue？That will help a lot. Thanks in advance, and have a nice day.

Hi Semi, Our engineer will email you later, if you are willing to do further analysis, please check your inbox. Thanks for your cooperation and support in advance, and have a nice day.

Hi, The orange light should be internet light; With your laptop connected to the C20 by ethernet cable, please login to the web interface as the instruction below：...

Hi, What is the version of the C20? Like it is Archer C20 V4 US or EU? You can take a picture of the bottom label of the main router. Besides, what is the current firmware version? Good day.

Hi, Here is the instruction to setup NC450. https://www.tp-link.com/support/faq/821/ Besides, please disable the 5GHz of the Deco M9 and disable the fast roaming at first. Once you setup the NC450,...

Hi, Thanks for your reply. May I know the model number of the main router? Have you ever tried to change some wireless settings of the main router? Like the wireless channel. When did you buy the 5...