I am currently using AdMob as ads network and it works very well.
I was covering case that users haven’t got the last version of google plays services, so for them, I don’t display ads from Admob because it can cause some crash (It appeared on a colleague phone as proof).
So I introduced Facebook Audience Network for these users.
And the performances are horrible, see by yourself in attached files
I read that the network is too young to ensure good fill rate, but I stay surprised…Does anybody meet that problem?
Thanks by advance!