I cannot reach my site, which is using a custom URL, from my normal IP in the United States (San Francisco).
With a VPN pointed to the UK, I am able to access the site.
The same thing applies to 'https://netlify.com" itself - I am unable to reach netlify.com or log in to my account from my regular IP - a VPN is required. For that reason, and for privacy, I have not provided my site url - it appears to be a general issue rather than one which only affects myself.
But it is surprisingly quiet, and https://www.netlifystatus.com/ is not reporting any issues.