A LinkUp will cause modification of TCP/IP object attribute 5

In an Extended Configuration Scenario, if the IP configuration is set by means of CIP_SERVICE_REQ/Set_Attr_Single and subsequently the protocol stack is set BusOn, the following issue may arise:

If a change of the physical link (LinkUp or LinkDown events) occurs in the mean time between the Set_Attr_Single and the BusOn, then the current configuration of the underlying logical network interface (in the worse case, a zero IP 0.0.0.0) will override the value which has been set into the object dictionary in the first place. Finally, with BusOn, this invalid or at least "old" IP configuration will be applied at the network interface, and no IP communication can take place.

The issue has been fixed. A change of the physical link will not set into the object dictionary the current configuration of the logical link anymore.