When you sau from two different networks, do you mean this server has two lan cards? When i was testing at home and connecting my laptop to a second lan card on the same PC with Openfire, i have noticed that my clients would logout and relogin every time my laptop goes offline (standby or restart). Second network is affecting all connections somehow. I don’t have time right now to dig up my description of this problem in forums, but you can try disabling one network. Though maybe this is not the issue if this happens only when many users are connected. Then maybe some info in the logs?
Somehow when i use Spark its run very well. I use Windows 2003 server, without posibility of standby or restart. I already watch info, warn, and ever error, but i found nothing suspicious.
Try setting a system property **xmpp.client.idle **with a value of **-1 **and check how your clients (Pidgin) are behaving then. You may restart Openfire after setting this, though i think it should work even without a restart. This setting will disable idle clients disconnection from the server. This can bring another issue, that some clients which are not normally logging out will stay online in your roster, though they would be offline in reality. Or you can set this value to say 600000 (this equals 10 min.). Then idle clients will be disconnected only after this period of time. I think default value is something about 1 min. now.