The log shows that a streaming connection gets closed after a few minutes of life and from the Server point of view the connection has been closed by the client.
However, the client behaves as though the connection had been interrupted by the Server.
Hence, something wrong seems to have happened in the middle.
The Server does not exhibit a general malfunctioning and a second session remains alive for all the timespan covered by the log.

You said that the issue occurs "every one hour", but you only sent a log snippet of 15 minutes.
Consider that only the full log, covering a few episodes that occur "every one hour", could allow us to make any hypothesis.

Alternatively, we could concentrate on one single occurrence of the issue.
Can you confirm that the Client was left unattended while the disconnection occurred?
As far as we know, the Client and the Server just could not communicate properly, which may be a network level issue, outside Lightstreamer.
Could you take packet captures on both client and server side and check if you see any packets not reaching the other side?