The three major cable providers provide a quick upstream. Unity Media offers up to 1000 kbit/s. In Germany there are 2000 cable kbit/s. Kabel BW is even allowed up to 2500 kbit/s. However, running a server is not allowed or restricted. Germany prohibits cable in the Terms (PDF) a server operating altogether.
Kabel BW is only slightly more liberal and allows in its FAQ any server that is open to the public. Thus one would protect a private website with a password. Solely Unity Media Server allows the operation for private, non-commercial purposes, provided that the data transfer volume moved in a normal range.
This has quite technical reasons. The cable network has been developed for the distribution of radio and television programs. There has already been thought of a return channel, this is limited to the frequencies from 5 to 65 MHz. From 80 to 860 MHz, the cable network allows only the direction from the supplier to the end customer.
The connections are available to each cluster, all hanging on a copper strand and are powered by a single glass/copper transition, only four channels are available, each offering a throughput of 27 Mbit/s net. Assuming a cluster size of 500 connected nodes, which fully utilize all their upstream, each participant remain about 200 kbit/s.