It could be that the router that you used was been hacked or something based from what you said. What I can advise is you can try to upgrade the firmware of your router, re-setup it once more.
Then once everything is fixed, try to change the default password of the router's GUI, secured your wireless network, use MAC Filtering, disabled SSID broadcast and other stuff. Among network connections, wireless connection is susceptible to attack and you should be able to secure them.