Stuck in optimization at -16% Negative Roi

[MartinB]

Hi folks, I'm working (I think) quite good through my process of otpimization.
But I feel like I don't know what else to optimize after the 5th round of campaign.


I took inspiration from the @Nick s tutorial:

Survey Pops - The Intermediate Guide

Our official intermediate course/guide created by @Nick that explains how to run Zeydoo survey offers using your own landing page and profiting from pop traffic using PropellerAds!

afflift.com

This night I managed to go from -27% to -16% and I feel that the green field is very close.

I have 2 offers running inside this campaign, both performing quite the same. So I let them running both.
One Geo targeting. Direct link. No landing involved.

I feel I should optimize something here but do not know how:

ISP:

How can i turn MTN Nigeria and GLobacom profitable?

Connection type:

I feel there is a huge opportunity also in here but I'm not really sure how to make it work.

Any advice from the gurus here folks in order to make it work to the green field?

Device model: all Green

Device Type:

Same here, I feel if I optimize the smartphone, it can be a huge win...but not sure how.

OS version:

Browser version:

Should I cut the Chrome Mobile 70 or maybe not? Maybe it's linked