I have recently installed a SonicWall NSA 250 in a county office. They all use the AS400 system, the IBM iSeries. Ever since the firewall was installed, the users have been complaining about the AS400 terminal sessions going unresponsive. Before the SonicWall this never happened, but now, according to the users, at random intervals, the AS400 screen will go completely black, and they need to close it completely, reopen their sessions and log in again. As best as I can figure, this does not happen during active use, the users have been idle for as little as one minute or as long as several hours.
I have opened tickets with SonicWall, worked for days, but they say it is not the firewall, it must be something on the iSeries. I called iSeries support, they indicated one nearby county had the same problem and fixed it... But no one could remember the fix and the documentation was gone.
I have allowed all LAN to WAN traffic and services going to the remote iSeries server IP address as well as allowed all WAN to LAN traffic and services coming from the remote iSeries server IP address. We did days worth of packet capturing, we are allowing fragmented packets.
We are at a loss here, and the users are becoming hostile. Does anyone have any experience with this? Our next step is going to be removing the firewall and running without one for a day to see if the problem persists.