[TooCreative]

I was on that site a couple of times but never managed to find out which routes offer a single cabin for yourself.

I would not want to have strangers sleeping next to me.

[johannes1234321]

During Cornona this probably is different, but here's the relevant page: https://www.nightjet.com/en/komfortkategorien/ganzes-abteil-...

[TooCreative]

Well, that is a page which describes the options.

Bit have you tried the "Book ticket" button?

For me, it simply goes to the start page.

So I still don't know how to find the routes that offer these options.

[eesmith]

https://www.seat61.com/trains-and-routes/nightjet.htm suggests that (nearly?) every route offers a single compartment.

That is, "Most Nightjet trains use Comfortline sleeping-cars built by Siemens in 2003-2005 for German Railways' City Night Line sleeper trains." and "Below: Comfortline sleeper layout. All compartments can be sold as a single, double or triple."

[TooCreative]

Well, have you tried it?

Every time I try to book a trip, the single compartment is grey and says that this option is not available for this trip.

[eesmith]

When did you try?

I picked 14 April 2021, leaving Wien Hvf (U) at 20:13 arriving Berlin at 08:55. "Sparschiene Nachtverkehr Nightjet + Anschlussticket Nightjet." "Sleeper Bed", "Compartment with 1 bed (Single)".

€ 216,00.

Bear in mind the comment at https://www.nightjet.com/en/ : "Due to the travel restrictions caused by the corona pandemic, we are reducing the Nightjet traffic to probably 8 February 2021 ... As a precautionary measure, no bookings are currently possible for the affected trains from January 10th to March 24th, 2021", confirming johannes1234321's comment "During Cornona this probably is different".

[lmm]

Almost all of them. Certainly at least Cologne-Vienna, Basel-Vienna, and Amsterdam-Munich back when it existed. What ones did you try?