Strange problem with Bticino binding and TCP buffers


I am quite new to OpenHAB, but a long time Linux user. I am having a strange issue with Bticino binding ignoring bus commands after it has been running for a few minutes.

The setup: I have an Ubuntu 14.04 LTS box, running OpenHAB 1.8.1 downloaded from DEB packages, following the instructions here:

The Java version is:
java version "1.8.0_72"
Java™ SE Runtime Environment (build 1.8.0_72-b15)
Java HotSpot™ 64-Bit Server VM (build 25.72-b15, mixed mode)
I have a Bticino bus connected via F454 web server.
In OpenHAB I have configured only two lights and one rollershade just for testing purposes.

The problem: Initially after OpenHAB is started everything works great. I am sending commands to the bus and I am receiving updates on the bus - i.e. if I use a physical switch to turn on or off a light that is configured in OpenHAB I see the command in events.log and OpenHAB reacts on the event by executing the rules I have made. After a couple of minutes, OpenHAB stops reacting on bus events and the TCP receive buffer on the TCP connection between the Bticino gateway and the java process starts to grow and never goes down. Here is netstat for this connection:

Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name
tcp6 275289 0 ESTABLISHED 15015/java

Anybody has any ideas on what might cause such a problem? Or further troubleshooting directions?