Upgrade went well.
I followed the dumb "user friendly" GUI instead of manual upload.
1. On GUI, updated from 1.13 to 1.15. around 3 minutes
2. On GUI, updated from 1.15 to 1.20. around 3 minutes
All settings are intact. I haven't done reset, all wired/wireless client are working
I did a power down of 885L and all the networking gear/cam/switch and restarted them.
It is running STABLE for 8 hours now.
There is a question in my mind, is the zero day bug really fixed using the GUI automated way? I think yes but cant really test it.