Problem I'm having with my wired Billion 7800 is it's fine for small downloads like 10mb 15mb it maxes out the line which is fine on speedtests. Get into 100-200mb downloads and it starts stalling as if under a lot of load there is a problem which can effect download speed.

Very interestingg stuff, Andrew. Anyway, the Billion is now on its way back to Amazon. I think I'll stick with ZyXEL.

I'm considering the same ARD as I just had an unexplained reboot. Can you tweak the SNR of the Zyxel I maybe better off sticking with my speedtouch and buying a cheap gigabit switch.

RAM or CPU issue - does it support PRTG and provide any CPU utilisation data?

Turning off wireless, changing encryption, and other software features may help. As can trying multiple versions of firmware if available.

Trying the latest firmware and so far so good. Billion are sending me some new firmware to see if we can solve the throughput issue. It's the wired version so no wireless to turn off. SNTP is supported from the Web interface but last time I used PRTG it was fairly crippled on the free version.