Hello Mellow ,
thanks for your answer. We dig deeper yesterday. It happens when we apply a OVPN config to the Router via gui. If I use the cli it worked. We try RUT9XX_R_00.06.08.3 and RUT9XX_R_00.06.07.7. The WIFI and the landing page will shown on every device. The login via landing page work also. But after login we don't have any connectivity to the internet, no ping and traceroute work. If I use a cable on lan1, I got connectivity. Next I will try to set the APN manually.