Browsers in Windows7 not receiving EventSource notifications

Question

We have websites which use Server Sent Events (EventSource) extensively for receiving notifications from servers.

One single machine with Windows7 isn't receiving them at all. We checked basic firewall settings but looks fine. Websockets checking websites also work.

Any idea?

Answer 1

Well, we solved it just by uninstalling "Bit Defender Internet Security" tool which looked fine when we checked but anyway there was something wrong.

Any additional thoughts or deeper advices will be welcome.