Supervised iPhone VPN always on results no hotspot/ mobile tethering

Hello everyone, I manage my iPhone via the Apple Configurator so that I can use the "VPN always on" function. I noticed that devices that connect to my iPhone via hotspot receive a self-assigned IP and therefore cannot access the Internet. I tried to configure the IP on the respective devices manually, unfortunately without success. So far I haven't found a solution online. This is what the installed profile currently looks like. I've tried all the settings there. However, a DNS cannot be inserted, for example. When I click the + nothing happens: Thank you in advance for your help. Best regards