[ONCE OFF] In-Fight Server Error

Platform, device and operation system
Eg, Android, Samsung Galazy s8, Nougat
Android, OnePlus 5

What were you expecting to happen, and what actually happened
I was in the middle of a fight, second enemy in Escaping Dragonrest.

How often does this happen? When did it begin happening?
Just happened 2 minutes prior to this post

Steps to make it happen again
not sure yet. restarting helped. So I guess this is more an FYI bug report.

Has this happened since???

no, this has not happened again since that day.