We built a site for a launch and it was unreachable for anyone on an Xfinity router. We only found out because we have an Xfinity router at home. There's no notice to the site owner.

Xfinity's Advanced Security draws on third-party domain reputation lists and blocks at the gateway. We found out a blacklist called SURBL had flagged us. Not sure exactly what tripped it. Since then I've hit the same block on 10+ unrelated sites and told the site owner. Now sharing with everyone here.

How to check whether it's happening to you:

https://spa.xfinity.com/check_url_status If blocked, look for the upstream list: https://mxtoolbox.com/blacklists.aspx Report at https://spa.xfinity.com/report and call them nonstop (reviews take ~3 business days) and get off the upstream list too.

Trying to help get this out there so it happens to less people who are launching products.