Duane Carlisle

You could try hooking directly to your modem with Ethernet and see if it behaves the same as when you're using all your other equipment. If you're using wireless and it's slower than the Ethernet connection, try testing right next to your wireless unit. If it's faster, then you are likely too far from the wireless base station.
 
The ISP should be able to help you determine if the problem is inside your house or not
 
 

There are a variety of things that could be affecting your speed - at your place or externally (local connections, at your ISP, or on other legs of where your traffic is coming and going).
 
Give your ISP a call. Be polite, patient, and persistent. They should be able to help out. It may take more than one call.

Hooked up to Belong NBN provider,at rated speed 25Mbps speed Fibre optic to node 100 metre copper to residence router Gateway access, and Wifi to multiple devices. Max download speed about 24Mbps falls off to less than 1Mbps at times. what is going on to cause such a drop in download service.