First I need to know if the hotspot is running on the router? If it isn’t then your router won’t show up in the control center.

If it is working, but the router is showing down in the control center, that means our servers cannot see your router. Our servers send a life signal to detect the status of your router. This traffic can be blocked by a firewall in your network, or the SPI firewall feature on the router. Turning it off can resolve the problem. In DDWRT this is under Security/Firewall and check Disable beside SPI Firewall. Be sure to click “Save Settings” at the bottom of the page for this to stick.