By repeater, what do YOU mean? Folks use this term very loosely, and I need to be sure.
Additionally, depending on what you are trying to accomplish, it may not be possible.
If you are trying to expand your wifi, why use repeater? Just setup ANOTHER access point, with same SSID rules and PW as the original, and that's it. Roaming between the AP's will happen at layer2, not layer3. You would need a controller, and homogeneous AP's for L3 roaming.
ok...well, the repeater mode is usually setup on the root node. Meaning you really cant repeat with your setup.
However, using there is a work around, but it requires having a PC that connects wirelessly to your cable modem, and then share that connection via the Ethernet port on that PC, and connect the access point. Make sure you don't allow the PC to connect to the AP you setup.