Can I travel with regional trains from operators other than DB if I can "use any train" due to a schedule change?

Question

I had booked a journey with DB involving local public transit (S-Bahn/tram), IC, and ICE trains. Now DB changed their schedule so my connections no longer are possible and I now can "use any train". What isn't clear to me, however, is whether this applies to regional trains run by companies other than DB. Based on https://travel.stackexchange.com/a/184580/92456, which describes a slightly different situation, it seems clear that FlixTrain long-distance trains aren't an option, which is understandable. But, what are the conditions regarding regional trains? There is a regional train operated by National Express that would work well for me, but can I actually take that in this situation?

Answer 1

The "Zugbindung" only refers to long-distance transport (Fernvekehr) - in this case basically IC and ICE trains. Anything which is operated as Nahverkehr - regional trains (starting with an RE or RB) or the S-Bahn - is automatically excluded. (As a rule of thumb and if it helps, if a Deutschlandticket is valid on it, it's Nahverkehr).

From the DB site:

"Diese "Zugbindung" gilt für InterCityExpress (ICE), Intercity (IC), Eurocity (EC) und Nachtzüge wie EuroNight (EN) oder D-Zug (D). Für Nahverkehrszüge besteht keine Zugbindung."

my rough translation of which is:

"this "booked train only condition" is only for InterCityExpress (ICE), Intercity (IC), Eurocity (EC) and night trains such as EuroNight (EN) or D-Zug (D). For local/regional transport there is no booked train only condition".

When the "Zugbindung" is lifted, you can use any other long-distance train operated by (or in cooperation with) Deutsche Bahn, or any regional/local trains that get you to your destination. The "in cooperation with Deutsche Bahn" is important because this would cover you, for example, on a TGV between Frankfurt/Main and Karlsruhe (that then goes on to Paris), or a Eurocity train with Czech coaches between Berlin and Dresden. As you noted, Flixtrain is excluded, as is any other private operator which doesn't operate trains on the public contract model (this tends to be touristic railways).

You can take an earlier or later regional train operated by National Express to connect into or from your long-distance train even without the Zugbindung being lifted - indeed there are some cases where a given journey is not served by Deutsche Bahn at all, and in those cases the ticket is still valid.