why o2 internet was slow ?

????? ​@Saaaaaaaa  Und jetzt?

Because mobile internet is a shared medium.

You could check and report a disruption her https://www.o2online.de/netz/netzstoerung/

Hello ​@Saaaaaaaa,

We're glad you found your way to the o2 community and are registering here - welcome!🤗
It's not nice to hear that you currently have a slow internet connection. Have you been able to check whether there is a fault in your area using the link provided by schluej? If there is no apparent fault, you can report a fault there.

Best regards
Daniela