@ITS For your information, the Archer A9 does not support Print server feature. That is why the HP printer plugged into the USB port cannot be detected. It is used for the hard drive now. Good day.

@Chaplin The Archer C6 does not support bandwidth, while it supports QoS, which is the similar with bandwidth; But it has changed the basic setting and improved the algorithm/logical. You can refer...

@Drongo Do you connect all the three Deco M5 to the Archer C7 by wired cable? If not, please show me the current network diagram? What is the operation mode of Deco M5? Cause the C7 still works as...

@emixd Try to install the driver attached below:http://support.tp-link.com/f/55bcecfe49/?dl=1 After that, please verify whether you can detect 5GHz.

@isb21 Glad to hear that you figured it out finally. Congrats. For the channel supported by the Archer T1U, it varies due to the different countries/districts. Best regards.

@spt You can read this article: https://community.tp-link.com/en/home/forum/topic/173376