I ended up finding the solution to my problem, if someone else is having the same problem with the "IP not being whitelisted" even though it is. And if you tried changing the DNS to 8.8.8.8, turning off your vpn, creating new outbound and inbound rules for port 27017, and still you can't find the solution. Check your node version and make sure is updated, that was the mistake i was making, i checked mongoose version, express and mongodb versions and everything looked good.

It was the node update.