Not able to connect to mobile data -SMS & calls work

Hello!

I recently bought a Xiaomi Mi6 (OS Dido 7.0 Android 7.1.1) and I can't connect to the data. My carrier is Chatr (Canada). SMS and calls work.
There are no APN, and even after I create one with the carrier info, it doesn't connect.
Any ideas as to why this is happening?

Thanks in advance!!

The APN has to be the APN used by Chatr, not just "some APN".