I made a UbuntuCore image for OrangePi PcPlus whose WIFI is 8189fs.
The driver's sources is here.
I start the Core without Ethernet the first setup and set the WIFI configure as below.
Stop here all the time.
Then I restart the Core. This time we can see the wlan0 with a IP address.
Next, still stop here all the time.
Then I restart the Core with a wired network.
Maybe the wifi driver also have some problems.