How does Remote DVR know that you're remote?

I've used Channels for years but just recently purchased a NAS capable of Remote DVR streaming (Synology 218+).

Apologies if this has been answered elsewhere. When I leave the house and open the Channels app, it shows no tuners detected. I click 'Connect to Channels DVR', click 'Authorize', and then my tuners (and recordings appear) and I can view live/recorded content.

I expected to have to do this the first time. However, I seem to have to do this every time I leave my local network. Granted I've only tried this a couple of times, so maybe I'm missing something. I just assumed that the Channels app would somehow 'detect' that you were no longer on your home network (based on the IP range perhaps? Or just an absence of local tuners?) and would connect to the remote DVR. Is this not the case?

Thanks

(Disregard previous comment. Another network renumbering snafu.)

On iOS, at least, I only have to authorize once. Even if I quit the apps, restarting it lets me right back it.

Used to be, I thought, that if you connected locally you'd automatically be authenticated for remote, but that didn't work this time.

Oh yeah: "How does it know...?" I presume it looks at the IP address requesting the connection. It "knows" what it's LAN is. Every other IP address is remote.

Ok so if you leave home and open the Channels app, it automatically connects to the remote DVR and you get your tuners and recordings? Perfect.

The other question I had - let's say you're remote, and then you re-join your home network. The one time I tried this, it didn't switch to using my HDHR tuners on the local network. It was still using them 'via DVR'. I'm concerned that even once I get home it continues using my cellular connection (and NAS) for streaming content. Do you see it switch back automatically too?

Yes, it switches back to local automatically.

Which app platform/device? If it's not connecting to remote automatically that's a bug

Synology 218+ for DVR and iOS for the client. Although I'll say that after I posted this it's been working much better. I can drop on and off my home network and it seems to work well. It's been switching to remote every time I leave the home network.

When I re-join the home network, I notice it will sometimes still say that my tuners are 'via DVR'. Although if I click 'Scan network for tuners' it will switch immediately to my local tuners. Do you mind sharing what the algorithm is for updating this?

My only concern about this scenario is if it continues to use my cellular connection to stream even when I'm back home and on Wifi. Although I guess this is highly unlikely as I'm pretty sure iOS uses a Wifi connection over a cellular connection for all traffic if one is available. It's possible it may be using my wifi connection to talk to my public IP and then to my DVR!