Hi @ajccoach . The Deco manual doesn't mention QoS or bandwidth control for the WAN connection. Have you found a setting on your router?
You don't need to worry about download limit. Upload limit is set to 95% of upload speed. For NBN50/20, try it at 19,500 Kbps first.
If you run the TPG speed test and the upload part runs smoothly, you may not need to set it. If the upload seems to stop and start, then set the value.