We have noticed an apparent unreliability of Web Player connections to both plain servers and cloud servers when the user is opening multiple connections to the same NoMachine server.

This problem is due to the limit on the maximum so called "persistent connections" that a browser can open to the same physical host. Such limit is by default 6 "persistent connections" on Firefox.

More information about "persistent connections" on Firefox is available here: http://kb.mozillazine.org/Network.http.max-persistent-connections-per-server

Given these 6 "persistent connections", Firefox is able to open 3 Web Player sessions on the same NoMachine server, since each Web Player session requires 2 persistent connections.

Exceeding these 3 sessions by opening a fourth session causes any of these sessions to fail randomly. It was verified that by increasing the limit in Firefox to 10, the maximum number of Web sessions that is possible to run is raised to 5.

We plan to change the implementation of the Web Player so that it doesn't require such "persistent connections", even if this may possibly affect the session's performance. However, this is not something we have given high priority to, at least for now. It must be recognized in effect that running more than a single remote desktop session on the same client, connected to the same remote host, is not something many users are likely to need.

More cumbersome is such limitation when accessing, through the Web Player, sessions running on a Cloud Server. This limitation of 6 maximum "persistent connections", or 3 Web sessions for Firefox, applies to the total connections that, from the same client, is possible to run to the same Cloud Server. Fortunately, as we said, it is always possible to go into the browser's setting and increase such limit.

To increase the number of "persistent connections" in Firefox:

1) Open the Configuration Editor and list the Firefox Preferences by pointing your browser to:

about:config

2) Look for option:
network.http.max-persistent-connections-per-server

3) Set this option to an appropriate value.