Video doorbell system with two-wire, new construction

Yes, it exists. You can also do PoE (LAN over power) over 2-wire. Some offer that, I have multiple good experiences with 2N (Verso IP or recently the Verso 2.0 with better camera). There are definitely adapters with LAN > 2-Wire > LAN, which are simply called "2Wire" by 2N. It's basically nothing other than Powerline (e.g. from Devolo) with slightly fewer disadvantages. But it works.

Not at all. We are not transmitting 4K here and for HD well under 100 Mbit is sufficient. There are just more devices in between (converters from LAN to 2-wire and back) and you have a media conversion. Otherwise, you can do it and it is better than Wi-Fi as well. But make sure you really get a system with LAN over 2-wire and not a "real" 2-wire intercom. THERE the quality is rubbish.

That sounds great and I’m somewhat relieved. :)
Thank you for the concrete tips and what to watch out for!

our single-family house is about to be completed.

I am glad to read that.

Now it's about, among other things, which doorbell system to install.

That is indeed disturbingly late, and surprises me (your architect is not yet eighty). WLAN was certainly not invented to compensate for disinterest and/or incompetence of electricians. Powerline is already not so bad, but the rule still basically applies: "only an empty conduit is a good conduit." Reopening the plaster should be a matter of honor for the architect (and is also more pleasant than going to his professional liability insurance in a penitent's garb). Doorbell wire is, in my opinion, definitely far beyond the retro tolerance threshold. After all, one does not go on the internet with a mechanical typewriter ...

My elsti also had an irrational fear of conduit pipes that penetrate the outer shell. Something to do with the blower door test. I don’t know why, because as far as I know, a plug is simply put on then. He also absolutely didn't want to lay a pipe in the attic but only cables directly (as preparation for photovoltaics). Maybe it’s the same with that electrician?

Where is the problem? The bell wires in the empty conduit can be ideally used as a pull wire for the LAN cable… :cool:

My elsti also had an irrational fear of conduit pipes that penetrate the outer shell. Something to do with the Blower-Door test. I don't know why, because as far as I know, they just put a plug on it. He absolutely did not want to lay a pipe into the attic but only direct cables (as preparation for photovoltaic).
Maybe it's the same with the electrician?

Completely absurd, indeed. We had a core hole drilled for the extractor hood by the electrician, and the Blower-Door guy simply sealed it with foil and gaffer tape. That reminds me, we also have empty conduits on the roof, which the electrician also taped shut at the bottom.
Nobody made a fuss about it.

By the way, the Blower-Door test was excellent, it would have qualified for KfW55.

But what I don't quite understand... I watch media libraries in HD over Wi-Fi in hotels... why should a doorbell not be able to send a clean HD image via Wi-Fi to the router in the HAR, which is usually not even 5 meters in a straight line from the doorbell?
I mean, that might be so, but it definitely isn't because of the Wi-Fi, but because of the manufacturer.

Bosch manages that with their outdoor cameras, they don't even have a LAN interface.
Maybe that would be an alternative? Waiting for the Bosch Smart Eyes II for outdoors. It has everything you need. Combine that with a simple doorbell that informs you via app that someone rang. You do the rest with Bosch...

You, I’m also in the East (well, in Berlin, but really far in the East there) my electrician guy is also an Ossi. Here in the residential area, no one follows any rules (floor area ratio exceeded, driveways not paved or paved but probably not by a company with permission, regularly burned garden waste in summer, lawn sprinkling during the day, strips built up to the street even though the building authority said 5m must remain free, etc. etc.). But the guy was just the type who thought he knew better. To be honest, I almost blew up a fuss over the empty conduit because it was arranged differently. But at some point I got fed up and just wanted nothing more to do with the GÜ and all his people.