Hello Guys:

one confusing problem is appeared during the network redundancy test. the following picure the about network diagram.

And when the TIA Portal is online, it is showed the every connection is in good condition in topology view. 

But when ethernet cable was disconnected step by step. parts of connection are disconnected, the system still can be working well.

But parts of connection are disconnected the system is down. it must be reset by people. whatever the ethernet cable is connected or not, the failure can be reset anyway. it seems the network's reconnecting is too slow after one way is broken. the redundancy way is taken control too slow. 

can you give any suggetion?

Hello zhjp2023

Perhaps here are some useful information to this topic:

https://support.industry.siemens.com/cs/de/en/view/109759619

bye  Murof