Hey there,
I would love to see Link Capacity reported on your devices. It would be useful to have both the RX and TX of a wireless link report its total capacity i.e. the maximum throughput it’s capable of in a given moment. That stat acts much like an ethernet’s negotiation rate for someone like myself. I can use that statistic to report through monitoring on whether the link is reaching congestion or if it has breached it when capacity drops/fluctuates etc.
Hi RetralE,
Welcome to the forum and thanks for sharing your idea! I completely understand the value of having real-time Link Capacity stats that report the maximum throughput a wireless link can handle at any given moment. However, this is actually a more complex question than it might initially seem. Allow me to explain, and please feel free to correct me if this isn’t what you meant at all.
As you rightly mentioned, it can be really useful for monitoring congestion and understanding link performance. Airtime utilization can provide insight into how much time the radio is actively in use, and the throughput stats indicate the actual data being transmitted at any given time.
For example, the graph in cnMaestro under the AP performance tab provides a visual (I’m pretty sure this is the airtime utilization because it says airtime)
Additionally, throughput in kbps is displayed here as well:
Regarding the “theoretical max link capacity, at a give moment” you’re likely already aware that it’s largely determined by factors such as Modulation and Coding Scheme (MCS), spatial streams, and channel width.
For instance, with a 2x2 client STA *operating on 802.11ax (Wi-Fi 6) at 20 MHz, the max link capacity can be estimated based on these factors. With 1024-QAM for high modulation and 2x2 MIMO, you can calculate the potential throughput under ideal conditions.
So in a way, you already know the link’s theoretical maximum capacity. The key is understanding how close the link is getting to that capacity during actual operation. For the total bandwidth used just measure the physical link switch port attached to your AP.
So the airtime utilization graph is more about time spent transmitting rather than the amount of data or capacity used. For example, you might be transmitting a small amount of data but still use a significant portion of the available time (airtime).
Channel utilization % ← We want
With a new Channel utilization graph we would see the amount of data transmitted relative to the total available bandwidth. If you’re transmitting large amounts of data, even if the airtime utilization is lower, you could have a higher channel utilization. So what you searching for is the channel utilization I think? 
Retry rate% ← nice to have
IMO to further asses how efficiently the radio link is utilizing its capacity, we would need to monitor the retry rate. If the retry count goes up significantly, it often indicates that the radio is hitting its limits. By that point, airtime utilization would likely also increase, offering a good indicator of congestion or nearing capacity (e.g., 90% utilization) for now