I see.
The only strange thing is
Header 9 - Keep-Alive: timeout=5, max=100
which is not produced by LS Server; and the related
Header 10 - Connection: Keep-Alive
which is never sent by LS Server on HTTP 1.1 responses.
This may hint that something acts in the middle.

Anyway, we wait for the logs, because some request parameters can also cause the Server to interrupt the response.
For instance, settings for polling or for client inactivity checks.