Bungee Problem

Hello everyone!
I have got a problem with my bungeecord server.
So, I have created a bungee cord and advanced it (on fortwarding).
It worked perfectly. Even my friends from other countries could join on my server with the IP of my internet.
But today it stopped suddenly. I don't know the real reason, but if anyone could help me I would be SOOO thankful!!!
Thanks in advance!!