If you use Silicon Dust's software, then this is the case. If you don't use their software, it's not necessary.
(The reason is that the HDHR tuners "phone home" every hour or so. Part of the process is for the tuner to refresh its internal DeviceAuth
, which is a token that SD requires when receiving guide information. Since it's based upon the channels that the tuner has scanned—rather than your location or cable provider—it's still sometimes inaccurate. Channels instead uses a different manner for guide info for the DVR, so the tuners do not need internet access.
SD's software also requires an internet connection to even operate. The client/player is actually a JavaScript application that is downloaded when the app starts; no internet, no download, and therefore no app. Also, their DVR stores all recording rules in their "cloud", and the DVR queries it every 4 hours to refresh its "might record" list; SD's DVR only shows a list of programs that are candidates to record, which is far less accurate than Channels' Schedule.)