I always dread the moment we cross the French German border by train when visiting my family. The internet cuts out basically immediately, it's really impressive, especially on the Saarbrücken route.

Yup, I faced the very same recently crossing back into Germany from Denmark. Suddenly, nothing worked anymore. I dread the time I have to take the train to a different city, as Internet mostly only works when close to the actual stations. It's even worse now that many routes got longer as the trains get diverted due to maintenance work.