Website is loading slow, but only in Germany with two providers

Hi Community,

i have a really strange behavior with my website. I have activated Rocket Loader and Caching through CF.
When i test my website on Pingdom or Webpagespeed, where you can select the country (germany), my website is loading very slow (>15 sec.)
BUT, when i do the same test in England or even in Tokio, my Website reaches a loading time under 1 second.

I have tested this behavior with multiple devices and providers in germany now. My results are, that 2 of the biggest providers (Unitymedia and Telekom) are loading the website really slow. Sometimes i even get a 522 error. The only provider that is loading fast is Vodafone, plus i dont get any 522 error.

Here are some Screenshots from the test.

How can this be? Is the German CF CDN for some providers slower than others ?

Thank you for your help.