The EPIPE error is a communications error.
Here's another description of this type of error:
"This is very likely a broken network connection. That is to say the network connection was broken. You should check your /var/log files on BOTH the client and the server systems to see if there is anything that would indicate what went wrong that cause the connection to break. For example if the rsync on the server side died, it would drop its side of the network connection, and you would receive EPIPE error (Broken Pipe)."
In this case, the error message indicates the Presstore client lost its network connection to the Presstore server. The Presstore server then reported a 'broken pipe'. One possible workaround would be to try to reduce the bandwidth limit in the Presstore client configuration, thereby slowing down the sync process - which would hopefully result in a more stable network connection.
As this is really a network related error, other possible solutions would be to make sure you use the latest OS, the latest drivers and to make sure your computer hardware and network infrastructure can handle the load a sync or backup generates.