I haven't been able to make calls properly for a few weeks now and sometimes I can't be reached. After restarting the mobile, it works for a few hours, then the problem occurs again. According to Yallo, the reason is that the 3G antennas are switched off and I would have to switch Volte on/set it as the default. But this is not possible in the settings. Does anyone know a solution or have the same problem? Oppo is unfortunately not available for help and chatgpt has not helped either.