I'm trying to set up a system where the clients have to use a voucher to sign in/authenticate themselves before being allowed access to the network. I've already done the settings on the portal and voucher page but when testing, one client is not redirected to the authentication page at all. Their phone (mid-high range phone) shows that it's connected to an insecure network but doesn't show the "authetication/sign-in required" below the network name. They also cannot upload or download any data while connected to that network.

Another client's phone (low-mid range phone) shows the "authetication/sign-in required" and automatically redirects to the authentication page, but receives a timeout error while trying to load the authentication page like shown in the picture below.

How can I fix this? Any help would be greatly appreciated!