About Stream-sense:

When a streaming connection doesn't yield an answer within a few seconds, a polling connection is tried.
Intermediate nodes with a buffering behavior will cause the streaming connection to delay, but slow clients and slow connections could also have the same effect.
Note that, in the latter cases, the subsequent polling attempt may timeout as well.
On the other hand, the Allegro version limitation does not prevent streaming.

Unfortunately, the Stream-sense is not directly notified in the Server log.
With the current Web Client Library, you have to manually recognize a
create_session
Starting new session
STREAMING_IN_PROGRESS
create_session
Starting new session
Polling () to session
pattern from the same client. We can do it for you, if you have any doubt, but we need to analyze a log that spans a few seconds.

About unknown clients:

Ok, so you are not the only user of the test system (I suppose that other people in your organization are testing the connectivity).

About blocks in the data flow:

Unfortunately, I didn't understand the remarks below:
- Client didn't stop suddenly, because open two page browser contain same receiving data from lighstreamer. (Make client open just 1 instance even open two browser, or make 2 instance with no problem). CMIIW If one client open two web page, in one browser, is it automatically create 2 instance... how to make sure client just using 1 instance, we cannot preventing client open 2 browser with one page, isn't
Do you mean that, indeed, the blocks are related with cases in which two instances of your application are running within the same browser instance?

Otherwise, you should try to reproduce the issue in the simplest possible way, by starting the Server and operating on your clients.
Then you should attach a full Server log, together with your notification of the time in which you noticed that the data flow got interrupted.
It you had the opportunity to test the system and reproduce the issues while no external users access the Server, that would make the log far more readable.