Tekkit Classic not starting

[Morphineius]

My Tekkit Classic has recently stopped working, I have found the crash report and when I start it I get asked if I want to play on offline mode, even though im online.

Launcher is on the latest stable build, same story with Tekkit Classic

Here is the crash report, click here

edit: When I try to join servers it gives me an error message: HTTP response code error 503

Thank you for your time