I am using wired network for the CAM.
When the streaming lost, the configuration page still works.
i.e. I can still reboot the cam via browser. And after reboot, the streaming comes back again. Yet, it will lost after a certain period of time.
(Configuration page has no problem at all. I tried to connect to the cam using Wifi / LAN on my laptop, the results are the same.)
And at the same time, my other cam with older firmware works well.
So, it is not the router problem.