I try changing the Mobile WAN from the original <TPG_Telecom(default:1)> to <Vodafone(default:2)> to test the speed. Now when I try to change back to <TPG_Telecom(default:1)>, I am getting <Error code: 89527, The APN field is required>, but the APN field is greyout plus the APN field is initially blank for <TPG_Telecom(default:1)> setting. How to I change that ?   ... View more