My provider did some network changes the morning of February 7. This is not atypical - it happens once or twice a year, and they alert me a good two or three weeks in advance. It usually comes and goes without issue, except maybe I need to update DNS with a new IP for my domains at Godaddy.
This time though they did something I didn't know they'd do. They wrapped up their network behind an extra later of NAT (network address translation), so the IP my router said I possessed was different than what remote websites told me I was at. This broke incoming traffic. Traffic on port 80 (HTTP) would arrive at the external IP and not know how to route to my server because its a device I don't control, unlike my router which is set up to forward all port 80 requests to the server. I finally got traffic coming directly to my router, but then it was only working for me. Had to work with my provider to just totally disable NAT so it became visible to you fine folks.
I'm not a network engineer but do have a Computer Science degree (two, in fact, if you count a Master's degree distinct from Bachelor's) so I know enough about what should happen when things work right, but when things don't I have to research and experiment until I discover the solution. This one was rather challenging and took a few days to solve. Work, personal, and social demands keeping me from spending more than a little time on it in the last week, which delayed the fix.
Thanks to Moge for lending some remote testing support.
