It is quite easy to connect an iPad to the ASIAIR's LAN port, which should not be a surprise.
Turn on ASIAIR and wait a minute or two for it to completely finish booting.
When the iPad is connected directly (I use Lightning to RJ45 adapter on a three year old iPad Pro) to the ASIAIR LAN Port, you should see an "Ethernet" item appear in the iOS Settings (just under the WiFi item on iOS 14.0.1).
When you select "Ethernet," the Ethernet Settings on the iPad should show that it is connected to "USB 10/100 LAN." Just default Ethernet Configure IP to "Automatic" and let the iPad figure it out for you. If you drill down, you should see the IP is 169.254.247.xxx.
When you launch ASIAIR, the ASIAIR Settings window should show that "Wired Ethernet" is "Connected." Again, give it a minute or two to finish connecting if you don't see it at first.
The speed is pretty much similar to connecting the ASIAIR directly to your router, and with the ASIAIR accessing the router though 5 GHz WiFi band. If you find a Gigabit LAN adapter, I think the speed would be better (the Raspberry Pi 4 LAN port clocks in at really close to 1 Gbps).
If it does not initially work, to reduce confusion, turn off WiFi on the iPad since there is no way to turn WiFi completely off on the ASIAIR. Or just walk 3 meters away from the ASIAIR Pro if you have a long LAN cable :-). You need to keep WiFi or Cellular Data in the iPad on if you need to connect to the Internet, of course.
If you are out in the field, connecting the iPad directly to the ASIAIR LAN port is definitely a good option. Also, it is arguably the most solid way to update the ASIAIR firmware even if you are at home.
Chen