For iOS/iPadOS, there is only a single app. All other platforms (including tvOS/Apple TV) have 2:
Submit diagnostics from the app after getting the tuner error
Tried the Channels DVR app on Apple TV and got same error. Diagnostics submitted.
Diagnostics were submitted.
I tried a little experiment last night - second Apple TV in house 2 had not been connected to Channels DVR in house 1. Before connecting it, I verified that I could watch channels from the HDHomeRun which is located here in house 2 and connected to unencrypted Mediacom. It worked fine as expected. After remote connecting to Channels DVR in house 1 (which works great!), I could no longer access channels coming from the HDHomeRun here in house 2. Tuner Not Available.
Thanks!
I am not 100% sure how the magic works with server, but this sounds like it makes sense. Maybe.
As long as you are not connected to the server in House #1, the app works fine with the HDHR in house #2, with the ATV in House #2.
When you hook up to house #1 is when the issue starts and it sounds like the reason might be because there is no connection from House #2 back to House #1 for the server to feed a 'signal' back to House #2.
At House #2, you are remotely connecting to House #1 via the Channels service and it can feed you the 'signal' for the HDHR that is at House #1, but that HDHR is local to that server, so it has access to serve out live channels from that local HDHR. It is just like it would be if I am outside my house and use the service to access my home's Channels DVR server.
But, that server, at House #1, does not have local access to the HDHR at House #2, so it cannot serve out any channel from House #2's HDHR.
You only had the standalone app working at House #2, before this, and it works with what is local to it, so it works fine with the local HDHR.
Once you connected to the Channels DVR service at House #1, everything has to go through that server and the HDHR at House #2 is not local...or set up with the DVR service at House #1.
So, now I kind of go back to my original line of thought...it sounds like you need a VPN setup between the houses, to allow the HDHR at House #2 to be local to the server at House #1. House #1 server does not need the VPN to serve out the channels, but it needs it to have a local connection to use the House #2 tuners...which is why you are getting the no tuner error...the server cannot see that tuner...even if the app can see it, locally, the server cannot see it locally.
I will let the devs say whether I am way off base, but it makes sense to me.
I think I'm following what you're talking about.
Tried explaining this in another post never replied to. TVE channels not displaying in On Now or Guide when filtered to Favorites So I found another reason not to use the iOS client.
I have two Channels DVR's at House#1.
House#1 DVR1 only has a source of HDHR Prime.
House#1 DVR2 only has a source of TVE.
The problem is the client device can see the local HDHR's even if they aren't enabled in the DVR being connected to.
So I'm at house#1 and I connect my iOS client to DVR2 (using local at home with the IP of DVR2) which only sources TVE, the client still sees the local HDHR tuner, since I think that's the way Channels started. It doesn't have to use a DVR to see HDHR devices that are local to it, but does for TVE or M3U sources.
Of course using remote access with two servers complicates things.
I am not set up with 2 servers at same locale...when you are remote, do you use different ports and port forwarding to distinguish or does the Channels DVR service allow you to pick and choose which server you want, remotely?
Then perhaps we're talking about different things.
I don't use remote access, only have two Channels DVR servers at the same house#1 location that I choose to connect to locally in my client devices by Connect at home via IP address of the servers.
I was trying to point out that any Channels client will see a local network HDHR tuner, whether or not you have any local or remote Channels DVR Server and if you do, whether or not it's a source device for it.
I gave up and worked around it since nobody replied and obviously by using two servers we're unique.
No, you are good and we are talking about the same thing. I edited my last post to more clearly convey that I was saying that I don't personally have 2 servers at home. And then I was replying to your last sentence about using remote access with two servers being complicated. I thought you were saying you actually do connect remotely with 2 servers. 
I think you have it correct. The odd thing is that the ATVs in House #2 can see the local HDHR that is in House #2. It shows up as a source, I can scan it for channels, it finds channels, and the content shows up in the guide. My guess is that when I select something to watch, the app is going back to Channels DVR in House #1 to try to access the tuner and it obviously fails since it has no way to connect to the House #2 HDHR. I must be the first to have tried this or to at least surface the issue.
Yeah, I think the key was the server taking ownership after it was connected.
Can you uninstall the DVR app and just install the standalone and see if it reverts back to just seeing and working with the HDHR in House # 2?
Or, can you try setting up a VPN, between the houses? I am pretty sure your experience for HDHR channels from House # 2 would suffer...maybe considerably.
Your best option, while at house # 2, may be to use HDHR app for locals at House #2 and Channels for recordings or locals from House #1.
If you need to record channels from House # 2, you might consider setting up a server there, as well.
To the Devs: I know if I want to remotely connect to my home server, I just log in to my channels account and, as long as I have it set up on the server, I am directed to my home server. With Channels DVR, I know I can have more than one server setup and I know I can select by IP, when I am local to those servers. If I did have more than one server set up, at different sites, how can I access them remotely and select which one I am connected to? Or, do all my servers converge and I get the best of all the servers? If they converge, then the best thing for seaside63 would be to set up a local server at House # 2, correct?
The app can be connected to only one dvr at a time.
Your dvr subscription gives you the ability to expose one dvr server for remote access.
Multiple dvr access and mixed local/remote dvr or HDHR is not something we have tested and we don't know how the code will react to such a setup.
Thanks for the quick reply. Can you select a specific remote server, if you have more than one? I know how to do it locally, with the IP address.
It's not possible. There is one remote access domain per account.
I guess you could go into each dvr and turn off/on remote access based on the one you want to expose and connect to.
That makes sense.
So, seaside63, I go back to the suggestion of using HDHR app for House # 2 live channels and Channels DVR for recordings or live channels from House # 1.
BTW, Happy New Year, everyone.
Do you have access to TV Everywhere from Mediacom? If so enable on DVR at house 1 and have access via remote access. This is a work around but might give you access to more channels at house 1
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That would be a good idea but our Mediacom is covered by HOA dues and we have no login info which could be used for TVE.
Yes, that would work. Iām not a fan of the HDHR app and having multiple apps would fail the wife test. 
Most everything is working as expected. Remote DVR and local HDHR show up as sources. Guide date for channels from both sources are merged, etc. The only issue is the final step of tuning into a local HDHR channel. Code would need to know source for each channel and tune to the appropriate source.
Haven't tried so don't know if it works, but...
Could you install both Channels apps (Live TV and Whole Home DVR) on your client device (ATV?) and use one to connect remotely to the DVR at house#1 and use the other to access your local HDHR at house#2?
Not sure if the two apps share settings.