Right, I now have no idea what’s going on.
http://my.hdhomerun.com/ showed no tuner when I visited it, so I hit the tuner’s IP address in my browser to check the logs, didn’t see anything of note (just a reference to the firmware upgrade I did yesterday), and reloaded http://my.hdhomerun.com/ - at which point my tuner showed up.
Checking the ATV Channels app, I now have all the guide info present.
The tuner has had the same IP address on the same network all along, and should have been able to access the internet the whole time.
It’s great that it’s working now, but I have no idea what broke it, or what fixed it (I work in IT so I like to know that things are fixed for good).
Any ideas, so I can potentially avoid this happening next time? It’s a real pain not having a guide.
Cheers.