xFinity Security blocks access to my French Banking Website

Using a rented xfinity modem, MacBook under Catalina, mesh wifi....all is good EXCEPT that the modem blocks traffic to my French Bank's website. I figured out that it was the modem and not firewalls or the browsers (Chrome, Safari) after being able to connect by tethering to Verizon's LTE network. I opened up xFinity Security's list of threats blocked and sure enough, there was my French Bank's website. Interestingly, after rebooting my modem, I was able to access the site.....for a while. I guess it takes some time for the modem to load all its security goodies. How can I get the modem to recognize that site, short of disabling the security feature itself? Appreciate any suggestions.