IPOC clients losing connection to server

[tandrist09]

We have several clients that out of the blue, seem to lose connection to the IPOC server?
This is turn, forces the clients to log back in, or freeze the client interface which requires to kill the service or reboot the PC and log back in. Anyone else seen this?
Thanks, Tom

[jtarjanyi]

Is there any firewall between the IPOCC server and clients? We have experienced loss connection due to blocked port by ACL of ethernet switches.

Unfortunately the IPO port matrix was not up-to-date, so we have to open big range of ports.