Those are very old versions that are end of life. I highly recommend upgrading to the latest 6.1.1 software (126.96.36.199).
The sensor ports will get disabled if either neighbor device loses link. You will want to check the neighbor devices to ensure speed and duplex matches on all devices.
If possible, you may need to isolate a single device by using a known good switch between the sensor and neighbor devices.
Thanks for you reply ,
I had already check all devices about switch , all devices configure is ensure matches(speed and duplex).
on the other hand,I had found something. the port mode is in-line-fail-open(port pair) in a sensor , the sensor just use a one port ( in-line-fail-open(port pair ) like use two port for in and out , when i search the google ).
I don't the configure is correct or not,I haven't change anything without upgrade software.it is a new task to maintain this product for me.