Seems the product is bricked

The router does not support curl

Some routers such Archer C5 V2, C8 V3/4, C9 V3/4, C3200 and so on can support up to 85 devices if those devices don't use too much bandwidth. Usually 30 devices is the recommended maximum number of...

How about a factory reset? Press the reset button or reset it under system tools. If no luck, you can contact support@tp-link.com

If you can get 12Mbps on your Mac, then the settings on the router should be fine. I suggest you change another cable to connect the box, reboot it or something.

Are your deco units working as router and repeater, or AP mode? Beside the update, did you change any setting on the deco? Have you ever reboot the deco and your router or modem? If you could,...