The firewall drops some frames during network communication, preventing proper operation of third-party applications.
Sometimes the firewall drops non-RFC-compliant frames during network communication. This may prevent proper operation of third-party applications.
To resolve the issue, disable the Stateful Inspection Level setting. This can be done in a centrally-managed environment.
The level of stateful inspection performed on datagrams in the firewall. Stricter levels are safer but may cause compatibility issues with network protocol implementations which do not fully conform to the standards. We recommend that you use the strictest level whenever possible.
RFC: Inspection according to network protocol standards. Datagrams not fully compliant with RFC documents may be dropped.
Disabled: No inspection other than keeping track of connections. Protection against DoS and other network attacks is lower than normally.
Note: The relevant setting is located at F-Secure Internet Shield // Settings // Firewall Engine // Stateful Inspection Level.