There’s no apn setting on iPhones with Vidéotron... it’s all managed automatically. It’s looks like that data roaming is not working on your device... I understand you wrote it’s enabled... but your device is acting like it’s not enabled. Try to disable data roaming, reboot and reenable it. If that doesn’t work, you will have to call Vidéotron to get this fixed.
Also, you should definitely upgrade to iOS 12... it’s really worth it on older devices like the iPhone 6s.
Thank you very much for the help. I did try rebooting and then was able to chat with Tech support when I got back to my room. They confirmed everything is set correctly at their end had me reboot again and this time it worked. Always works when you have tech support on the line. But again thank you so much for responding.