can't access bing.com

I have a strange issue:

90% of the time I can't access bing.com when on videotron's helix wifi. It happens on all devices connected to my wifi. If I switch my cellphone to use telus's network, all works fine.

I can't access bing.com, and then after a while I can access it again. Sometimes I can't access bing.com via edge but can via chrome, sometimes the other way around. soon after I can't access bing.com on either browser.  Later that day it'll start working again on both. But most of the time it's inaccessible. 

All other sites I use work just fine, it's just bing.com that poses this strange problem