Hey @mcd1977 !
It will connect to the best available network, so if there's no 5G in your area it can connect to the 4G/LTE backup. Make sure you check with sales to ensure once your area is covered with 5G so they can get you connected.
The product is intended for use on the Optus 5G Network. If you've followed the setup instructions and you still can't find an area in your home with sufficient 5G coverage, we wouldn't be meeting our 50Mbps satisfaction guarantee.
"During the term of your 5G Home Broadband plan, if you're not receiving speeds of at least 50 Mbps, or you're unable to receive a 5G signal, report the issue to us. "