It doesn’t seem as though there any any updates on the Netlify Status page: https://www.netlifystatus.com/
Have you made any recent changes or could you try a previous build?
Yeah I have ran some checks myself to no avail, I will ping @luke here for you and hope that it is resolved shortly! @yumo It is likely that you are facing the same issue as @Mistik but can you please provide your domain or App ID so that staff can help on an individual case basis if required.
Just to confirm one more thing, are your domains registered through Netlify? I checked my own sites which are up at the moment, however, the domains are externally registered.
These both seem to be working for me. If these are the netlify domains for the ones posted above, it definitely sounds like a DNS issue. It could line up to the IP changing as mentioned above although I am not sure why it would. Random suggestion, have you tried renewing the Let’s Encrypt certificate? Maybe it propagates through.