I just got my first smart tv - a Philips with Android TV - but I’m having some trouble setting it up. If I try to set up Live TV with my cable box hooked up with an HDMI cable, it doesn’t find any channels. When I do it with the cable plugged directly into the TV, no box involved, it finds a lot of my channels, but not all of them, plus the picture is noticeably not good and the guide doesn’t work. I can switch inputs, but it’s not very intuitive and requires we have two remotes. What can I do?
That's not how that works. Your cable box won't find or not find channels based on what display is plugged in.
As much as I understand, the Live TV option is to scan from Tuner Cards and not a direct HDMI connection.
Unfortunately, your options are limited. Cable companies have the ability to encrypt channels as a method of access control, and most TVs do not have the ability to decrypt them. The channels you are able to receive by plugging the cable directly to the TV are the unencrypted ones. To view the encrypted channels, you need a converter; either the one that is furnished by your cable company, or one that can accept a CableCard (which is furnished by your cable company).
About your only option to view your cable channels within the Android TV interface would be an HDHomeRun Prime. This can accept CableCard, but if your cable company places additional restrictions on channels, then you can still have issues receiving those channels unless you use the official HDHomeRun app.
Alternatively, cut the cord. Streaming services like Sling and YouTube TV can give you cable channels through an app that can better integrate with your streaming setup.
Your cable box is there to decode digital signals for higher-def versions of channels. Bypassing the cable box means you are seeing only the analog signals of channels, which will likely be lower-def and maybe fewer channels. Also, cable providers are quickly moving away from analog channel signals (so they can re-use that bandwidth to provide higher-speed internet service), so pretty soon (like my cable provider, Cox) you won't be able to see any channels without the cable box, i.e. bypassing the cable box will eventually not work at all anyway.
What you are asking for is a way to (a) convert the HDMI output from the cable box to streaming, and (b) control the tuner in your cable box to change channels, and (c) software to orchestrate it all.
For converting HDMI to streaming, there are a variety of HDMI-to-USB dongles on the market. For controlling (changing) channels on the cable box from your Android TV remote, you'd need an "IR blaster", i.e. an InfraRed transmitter that allows a computer to act as a remote control for the cable box. (Assuming your cable box can be controlled via IR -- newer ones are now bluetooth or some other proprietary wireless RF signal.)
I don't know if there is any software for orchestrating all this that runs completely on Android TV. (PVR Live app comes closest, but it relies on Google's Live Channels app which doesn't work in more recent versions of Android TV.) Traditionally, what people have done is run media-server software like Plex, Kodi, or Jellyfin, on a PC (a $50 Raspberry Pi works fine), then install the associated client app on their Android TV.
FYI, many people ("cable cuttters" like me) have bypassed your problem by no longer paying for cable TV channels (but still get internet service from the cable company), and then get "cable TV channels" via streaming services like Youtube TV, Sling, Philo, etc, which is usually a lot cheaper than paying the cable company for TV channels.
I personally subscribe to Philo so my wife can watch HGTV shows. I also get broadcast TV network channels over-the-air for free: I run Jellyfin media server on a Raspberry Pi, with the Jellyfin client app installed on Android TV. I also have an HDHomerun device connected to an outside antenna, and that HDHomerun device streams (over ethernet) to my Jellyfin server, which knows how to tune to different broadcast channels, then jellyfin acts as both a DVR and relays live broadcast TV to the jellyfin client on Android TV. (If you don't need DVR, there is an HDHomerun client for Android TV that can let you watch broadcast TV directly without needing a media server like jellyfin.) The HDHomerun boxes are fairly expensive, but there are also ATSC (digital broadcast TV) -to- USB dongles on the market that are pretty cheap (that you would plug into the jellyfin server box).
-david
Probably nothing tbh