"Request timeout" H12 Heroku error tying to access MongoDB Atlas
Alright it works, I answer to my own post in case someone is having the same problem.
I just forgot to add Heroku IPs in the whitelist so they can access to the DB...
Don't know how related this is but I was getting the H12 - Request Timeout error. Most likely because my .env variables weren't accessible in Heroku.
In the settings menu for my app I added them in the Config Vars section and now it connects.