My internet had been very fast for the past couple of months, with a ping of 28ms and download speed of 200Mbps. In the past couple of weeks its gone to an average ping of 144 and download speed of 38Mbps.
The modem hasn't moved. It's next to a window. I've tried restarting it. It has 2 / 3 green bars indicating average / good quality signal.
What should be my next step, not including going back to NBN?