This suggests a contention issue with the NBN tower you have been connected to. IE more users and demands for data than the tower or your local cell can manage at the same time.
@PhilT has suggested some alternatives.
The following also provides some official sounding advice. Standing up for your rights sounds good, but if one has given up the copper phone line there is one less option. Did Telstra indicate you could keep your copper phone line when offering you your NBN service?
P.S.
We’ve now had NBN FixedWireless for 3 months. Rather than stay with our ISP we went to Aussie Broadband. We’ve kept our other service for now, with copper phone line and ADSL until we are convinced the NBN is reliable and effective. It’s a small extra cost. Note we also approached Telstra re NBN. I’ve a 4G Telstra data modem for travel, which served also as a backup to the ADSL which has been unreliable on old copper. Zero prospect of that being fixed. . It has also served as a useful comparison to the NBN FW service. Unless one is a heavy user of streaming services or downloads we’ve found the mobile data service more than adequate, $45pm.
There are also offers from a number of providers to deliver a more permanent service to your home over the mobile network. There are varying reports on how well these do or do not deliver compared to an NBN service. TPG/iiNet are one using obviously the Vodafone network. My inquiries suggested they would be better than our ADSL2 service but not necessarily as capable as a good NBN Fixed Wireless connection. We are achieving 50-60Mbps down most of the time. Slowest at peak time has been 30Mbps. Upload speeds though have been typically only 3Mbps. 2 yellow LEDs for signal strength.
