Tito tried the putty? arp add example: arp add 192.168.1.100 a3:34:72:bb:04 arp show - you can see mac add to arp list in router.

Thanks a lot.

Do you have an active and installed network cards in your computer with WIN7?

have this message in router setting WAN port is unplugged,, check photo here Configuration without WAN is also possible in this device. TP-link is working like access point only with 4 ports switch.

I think but I'm not sure that you have to disable remote management on this router, because router has reserved 80 port for himself webserver.

Have you making test in local network area? Maybe it's problem with firewall?