"The ISPs customers are paying for a connection to the ISPs network, nothing more." They are also (usually) paying for a specific connection speed. If a custom

"The ISPs customers are paying for a connection to the ISPs network, nothing more." They are also (usually) paying for a specific connection speed. If a customer is paying for a 100mbps connection and Hertzner has 100mbps of spare bandwidth, but the ISP consistently only has capacity to relay 20mbps per second from Hertzner to my computer, then I would argue that it is the ISP's responsibility to upgrade their hardware so that they can fulfil their obligations to customers that they have sold 100mbps connections to.