It's good to know that I was not the only one to have the same problem! I tried all sorts of different plugs, but only a 5.00/2.1 would fit. I tried about 20 5.00/2.1 plugs until I found one that worked reliably. The socket fitted to the Aurora seems very loose, even with the plug that does fit. It seems the centre pin is slightly undersize.
Fantastic piece of kit though, especially for the very reasonable price
All the best
Nick