Michel,
Please take a look at this thread:
https://bbs.astronomy-imaging-camera.com/d/11389-asiair-pro-and-eero-mesh-network
I was able to clock close to 400 Mbps (== 50 MegaBytes/sec or 50 Mega octets per second).
When you capture an image, there are three steps.
The first step is reading the sensor's data into the fast memory in the camera (to reduce heat related read noise) and then copy from that memory to the Raspberry Pi's RAM.
The second step transfers the data from ASIAIR to the computer/tablet.
The third step is to scale and correct white point and display the image on the tablet's screen.
You can look for the point when your exposure finishes (the circular progress indicator). There is a pause before the green linear progress bar begins. Presumably, that is the amount of time to read the CMOS data into the internal memory of the camera and then copy that memory to the Raspberry Pi 4's RAM.
I believe the actual data transfer starts when the linear green progress bar shows up. And finishes when the green linear progress bar ends.
On iOS (iPad, iPhone, iPod Touch etc) a grey progress wheel then starts, centered on the image. My believe is that this is when the image scaling and white point correction take place. You can take away the option to do white point correction (in the Advanced option of the Camera Setup), and you will see that this step speeds up. Even my one year old iPad Pro (2388x1668 pixel screen) takes a significant time to perform this step; way longer than the data transfer time from the ASIAIR.
In short, you should be timing the linear green progress bar to estimate the Ethernet transfer speed.
This is why I tried to estimate the ASIAIR transfer rate by using the Samba server on ASIAIR to transfer multiple images (to reduce but not completely eliminate file system setup times) from a fast USB stick; and to a MacPro that has true Gigabit Ethernet (with two independent NICs, in fact). I didn't bother to try using an SSD on the ASIAIR since my believe is the USB stick is already fast enough. With that, I clocked 370 Mb/s.
If you are interested, I can try my 1000 MB/s Samsung T7 SSD (which should be faster than the 400 MB/s rated USB stick) and repeat the experiment with the ASIAIR connected directly to a NIC of the MacPro, instead of through a mesh node. I didn't bother with that since it would just be a best-case benchmark, and not my normal configuration when I use my ASIAIR (I have an eero mesh node next to my ASIAIR Pro, and both mounted inside a NEMA waterproof box that is lashed to my WO Mortar Tri-pier).
Chen