@Daryl_C80
Hello,
The Archer C80 supports QoS only, and it no longer supports set certain bandwidth for a specific device.
Below is the instruction to configure the QoS setting (there might be a slight difference from your web UI), you may try to give the specific device with high priority:
https://www.tp-link.com/faq-1532.html
We have noted this kind of request from other customers and our developers will evaluate how to improve it.
While if you want to purchase one that support Bandwidth Control already, here are the models:
Archer C50
Archer C2
Archer C20i
Archer A2
Archer A5
Nice day~