The Orange APNs are used when roaming to some countries. In the normal course of use, you should not see these APNs unless you are outside of Singapore. However, in some rare cases usually due to proximity to the border with our neighbouring countries.
Please select APN manually, then either Power Off your phone and Power On again or switch momentarily to “Aeroplane mode” and back. Note that there will be an approximately 3-minute delay before you are back on the SIMBA network.