Q-See QT4 用户手册

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After the router has assigned the DVR an IP address
Then return to the Network setup screen and enter this information into
Go back to  the Main Menu and click on the
the table in the configuration screen (shown below) and remove
Information Icon then Network Icon and write down 
checkmark from the th Obtain IP address
box
the IP address, Subnet Mask, and Gateway
Next click on the Apply button to save the addresses
assigned by the router
So the router does not change them.
The default ports are 80 and 6036.
NOTE: some routers, such as 2wire, will not let you use a static IP
address. In this case skip this step and stick with the DHCP address
STEP 2: DETERMINE THE NUMBER OF ROUTERS ON THE NETWORK
To Find out the Router information on your network, please download the router detection program from this link:
http://www.pcwintech.com/shanes-toolbox 
and click on Detect Multiple Routers
Download the program and unzip it, you will get the detect_routers application. Click to run
Click on CHECK NOW to detect how many Routers are in the network.