Atypically, I host this Web-site on my private server at home. When I got home today, I found that the DSL Modem / Router, which I rent from my ISP, had gone into a partially failed state, in which WAN access was still ‘normal’, but where attempts to obtain new IP addresses were not succeeding – i.e. My smart-phone could not connect to my WiFi when I got home. Also, maintenance access, which has only been enabled from within my LAN, did not succeed to check the router status.
The only solution I could think of, was to unplug the modem, wait for 60 seconds, and then plug it in again. This seemed to work, and my maintenance password to the Modem / Router has not been changed. I.e., I was not hacked. I was able to log into the Router again.
But power-cycling a router like that causes the network (LAN and WAN) to be unstable for several minutes. As a consequence, my site, and this blog, were not visible to the Internet from about 13h05 until 13h20.
I apologize for any inconvenience.
P.S. Also, I now have a new, dynamically-assigned IP address. But this could be routine, as my domain-name should resolve to the new address anyway.
(Edit 09/11/2016 : ) I gave the command at 13h16 the same day, to propagate my new IP address, and my own router, acting as my DNS server, reflected the new IP address, still within 13h16. It should not really have taken most readers until 13h20, before their browsers would have been able to fetch my URLs again.