I noticed huge lags today playing Arena (Android Galaxy S7 edge), but for the last few days it worked fine, before i had the same issues with huge lags ingame (several times), and on the next day it worked well again.
Also here i think the problem is not on the device side, but more on the server side, or what the server is requesting to do/send, i don't know.
But i'm having this since approx June/July, on some days i can barely play because of the lags (and loosing fights because of that), and next day everything is fine again.