How to activate IceFace/IcePush heartbeats Logs

Hello,

I currently face cases where agent desktop (thin client) gets disconnected from tomcat server
IceFaces version is 2.0.0 between Tomcat 7.0.23 and IE8 browser.

I think there is a network issue, but I have to analyse the heartbeats in server logs
I wiresharked interfaces very well, and see PING (GET) PONG (HTTP 200) between browser and tomcat.
I googled a lot, and all in all I only found a few logging options

************
org.icefaces.level = FINER
org.icepush.level = FINER
com.icesoft.level = FINER
javax.faces.level = FINER
com.sun.faces.level = FINER
************

And I placed them in the logging.properties file
I obtained those traces in the catalina.out file (with confirmation that Icepush version is 2.0.0) :
*************
Oct 26, 2018 1:53:33 PM org.icepush.servlet.MainServlet <init>
INFO:
ICEsoft Technologies Inc.
ICEpush-EE 2.0.0.GA_PUSH-148
Build number: 3
Revision: 24431
*************

But still nothing about heartbeat logs..
Can you please place me on the right way to activate heartbeat logs ?

if help appreciated
thank you