External captive portal whitout Radius server

Question

I am trying to implement an external captive portal using TP-Link EAP115 access point and OC200 controller V5.0.30 whitout Radius server. The captive portal that will collect the data will be hosted on an Ionos host (a normal website), so is not on the same network as the controller and I don't want to use a radius server. First, is it possible? Secondly, to authorize the client who will connect, a CURL request must be executed to retrieve a token which will be used for authentication, and to do so, it must be sent to the ip address of the controller.

curl_setopt($ch, CURLOPT_URL, "https://" . $controller . ":" . $port . "/" . $controller_id . "/api/v2/hotspot/login");

$controller is the ip of the controller that I can't find, I tried local addresses 192.168.100.179 since the client will be on the same network as the controller when connecting, I tried $_SERVER['REMOTE_ADDR '] since the client and the controller will have the same public ip when connecting. each time, I get the response CURL: timedout, like the address is not found I guess. Anyone have an idea that can help me? Thank you