There is no default bandwidth limit applied to our servers (VPS, VDS, DS); only our fair usage policy applies, which is as follows: 

To maintain fair network performance for all customers, traffic usage must align with typical server workloads. If the usage is exceptionally high or disruptive, Contabo reserves the right to throttle servers at its own discretion. Such measures are rare and only applied to preserve fair access.
 

Should your traffic usage ever exceed our fair usage policy, we will reach out to you via email, and we will do our best to find a suitable solution together with you.

For Virtual Private Servers (VPS) the options might, however, be limited. In such cases, you can upgrade to a Virtual Dedicated Server or to a Dedicated Server instead.