The longest single uninterrupted train journey currently possible on Earth

1) Claim in tweet: "This is the longest single uninterrupted train journey currently possible on Earth."

My counter claims:

1a) it is not a "single" journey (multiple transfers) which leads to 1b) it is not "uninterrupted" (multiple transfers). 1c) It is also not the longest journey possible because you can take many longer paths through Europe (mentioned in the comments of the tweet).

2) The submitted URL links to Twitter which in turn links to an article [1] with some numbers (cost estimations etc.)

[1] https://basementgeographer.com/the-longest-train-ride-in-the...

That would be fantastic as long as there is good service all the way.

When I was in high school I took a train with my older brother from the the US border to the Guatemala border, about 3000 miles. That was in the late 1960s, that train does not run anymore.

What definition of "uninterrupted" and "longest" are being used here?

tldr: the train journey starts in Porto (Portugal), stops in Paris, Cologne, Warsaw, Moscow, Beijing, Hanoi, and ends in Ho Chi Minh City (Vietnam). Total distance is 17.000 km, and the journey takes 275 hours (12 days).