Yes.

So, this information (sorry, only available in German) from the German partner NEG, telling Interrail passes are not valid, only applies to local journeys within Germany? 

https://neg-niebuell.de/PDF/PDF_Tarife/Tarife_Nieb_Tondern_2022_08_Netz.pdf

@Claudi. @Camilo can you please ask if the information on the interrail website and railplanner app about the Arriva trains from Niebüll (Germany) to Esbjerg (Denmark), if they are in pass network. The rail company that runs the small part of the train route in Germany says not valid. 

NEG runs 2 lines; its OWN to the coast, a ferryport to some islands, that is Niebüll-Dagebüll-this is traditionally a PrivatEisenbahn and does not accept-has never done-any normal german/international fares. This leaves from a side spur BESide the main station in NB-I know as I did that line on the 9€ ticket a few weeks ago in my quest to cover amap of germanies railways. There are a very few of such lines still ´open´.

NEG runs under CONTRact to ARV-DK (ARV is owned by DB and hence cannot run from DE itself-condition on sale then) the 2-hourly shuttle to T/onder. This is a thus a ARV train, but leased out to another comp-on german buses this is extremely often (in Auftrag) and on trains it also happens. THEse trains serve the normal platforms in NB Bahnhof. There is even a sign telling that on the doors and I quite remember also having read some note there that passes & all that were accepted.

In fact I somehow recall that on the DK-DE line they use trainsets that came from ARV-Danmark-thus with all the danish signage inside-when ARV itself got new trains.

AFAIK Interrail/Eurail indeed is not valid on the NEG trains. That means for Niebüll - Esbjerg, that you need an extra ticket between Niebüll and Tønder. In Denmark, from Tønder, Arriva operates the train and accepts Interrail/Eurail.

It may be that in practice the staff accept passes. A number of people used this route to avoid the fully booked IC trains from Hamburg into Denmark and nobody reported they had to buy an extra ticket.

Well because usually there is no conductor on the train.

but still wouldn’t risk it

Just to update this thread:

• Eurail/Interrail/German Rail Pass currently are yes indeed accepted on the Niebüll (DE) to Tønder (DK) section, and then onwards to Esbjerg (DK): https://www.neg-niebuell.de/PDF/PDF_Tarife/Tarife_Nieb_Tondern_2023_04.pdf
• The Passes are also being accepted Niebüll − Dagebüll Mole: https://neg-niebuell.de/index.php/fahrkarten/tarife/anerkennungen

We travelled on the border-crossing Arriva trains three times this week. Tickets were checked once on the Danish side. Interrail Pass was OK. No checks on the German side. One time passport control checks were done as the train waited in Tønder.

Other thing to note is that the Interrail planner thinks there are two different trains (Niebüll > Tønder, Tønder > Esbjerg and vice versa), when actually it’s just the one train going the whole way and no change in Tønder. DB Navigator understands that it’s the one single train.

This wasn’t a big issue for us but is misleading: the Interrail planner thinks there’s too little time to make the non-existent change of train it creates in Tønder. And therefore it tells you that you’ll have a 2 hour wait in Tønder until the next train .

Great, that's new then, for both of them.