@Carl as a product manager myself in a large tech company, I'm surprised this feature was 1)omitted in the first place as being able to collect statistics about device usage has been a common feature among routers for years, and 2) still receiving radio silence after this thread as well as many similar threads have received tens of thousands of views. There is clearly a gap in communicating the voice of the customer from these forums to the product team. The result is a subset of customers being hurt in the short-term and tp-link's bottom line being hurt in the long-term. I sure hope this gets more attention by the right feature teams soon. 

@Red-man-group 

There has been two types of request related to this.  1.  Where customers want to set specific limits in bandwidth usage because their ISP has caps.  This limiting is considered bandwidth control.  Some time ago TP-Link products took a different approach and switch to a more generalized and arguably easier to use version of controlling the traffic in your network by implementing QOS instead.  This is not to say that we aren't listening but as a global brand we generally make products to appeal to the masses.  Traditionally products that have features for a small sub-set of customers never do well.  QOS has been and likely will continue to be the traffic control feature that is deployed in our products especially with how tied to WiFi 6 it is.

The other is Traffic Statistics/Traffic Monitor:  Which is still available on some models like the Archer A7 or Archer A20.  However this feature shows how much traffic is used per IP address  not  per device and as you are likely aware unless you are using static or Reserved IPs, those IPs can change.  Also its just a monitor and not a limiter.   

These features are sent up to the PM teams but TP-Link by policy doesn't share roadmap information because it continually changes.  This is why when I do get request I tell customers to look out our Website every Friday afternoon.  This is when content releases happen and new firmware is added.  Release notes exist on each FW with what has been added or fixed.  This is the best source for results.  

Could you just start sending this request up, like, every day (or, better, every hour?) It’s honestly a deal-breaker and embarrassing for such an established name as TP Link, to be quite blunt

Edit: I'm also a tech manager, and these are kinda flimsy reasons. WiFi 6 has nothing much to do with Traffic Monitoring and vice versa. You keep a table of MACs on the internal network, sample how much data they're pushing or pulling (which you're already doing on many models) and then add a cron-like job to aggregate that into whatever mechanism your app is already using to ingest the data for these per-site monthly reports. It is not hard