In your case, you can login to the router's configuration page and do the wireless MAC filtering settings which is under wireless tab. Just add the client that you decide to block into the blacklist....

I suggest you configuring Dynamic IP as the WAN connection type. Don't forget to clone MAC address. With all the above done, is this router able to obtain the IP address 131.111.218.37 on the WAN...

:confused: i am confused! Maybe a network topology will be helpful to explain how do you connect the two networks. And what's that for? What's the WAN IP address on the TL-WR740N? Is it...

Are you able to receive office mail on the internet web mail? Maybe, you can try to decrease the MTU size on the router.

Hi. I am not quite sure that the router should be configured in dynamic IP or PPPOE. But we can check something else: connect the wall internet jack to your PC directly, then use ipconfig to pick up...

As far as i am concerned, you can only disable NAT when you use the router as a switch or AP. In other word, the WAN interface is not in use.