I'm in Toronto, Canada, on home fibre internet from Bell. Whenever I'm connected to my bell wifi, cloud sync performance is terrible. It takes multiple minutes to download a smart preview. If I switch to LTE or use another network, files download quickly.
I have not developed code for iOS in a long time, I do web/server based only now.
Back then, Apple generally hid the network connectivity from the developer unless you wanted to dig really hard. I doubt Adobe did so, since the application is not a device management tool.
With 400mbs up/down on the wifi; the prblem is likely elsewhere.
Unfortantely I no longer own any Apple devices, so I cannot help debug it. My normal next step would use traceroute to verify the network traffic to Adobe. Maybe Adobe can can chime in here with some server names you can verify the connectivity.
At a minimum, we should ask Adobe to turn this into a feature request to have a network connectivity status page.