This happens only to me and my collegue. We are conected to the same switch as the Openfire server. If i stop Openfire normally, our Sparks are reacting (start to reconnect). But if i just restart server pc or power off it suddenly, then Sparks are not reacting and showing roster without changes, 3 minutes and so on. They start to reconnect only when i pull off the the server’'s network cable out of switch. So i assume that switch is some how making clients believe that server is still online (some packets/sessions stuck in switch?? weird). The same was happening with Exoduses. When i was restarting server pc after some OS upgrades, Exodus wasnt reacting, until server OS was booted on and Openfire service starting to load. I cant say that it was exactly that moment, but it seems that only new instance of server was breaking that “stuck sessions” in network.
Maybe there is some way to make Spark notice that server is not really online anymore? Keepalives beacons form the server?