Are you getting the 4G LTE Signal strength bars showing and do you have the SIM seated properly in the modem.? Can you connect your PC with a LAN cable to the Huawei Modem and enter 192.168.8.1 into your Browser and select the Wi-Fi screens to see if both SSIDs have been Disabled. If they are Enabled, and not visible to any of your Wi-Fi devices, likely a faulty modem; suggest you contact Optus to see if they can verify replacement process.
Ask them to also verify if your firmware level is up to date in case an update has corrupted settings.
