Please follow up the below steps:
1. Modem-PC by wired connection, then try to open that website again ( please reboot Modem one time before you connect PC-Modem), if it working fine, that means the issue related to your router.
2. reboot Modem and Router together , then check if you can open that website?
3. try another PC or use Cell Phone data, then check if you can open that website?
4. few of website with IP Restrictions. Please make sure that website allow the Canada IP Address visit the website. If you not know your IP Address, please open : http://www.whatismyip.com , check your IP Address