I've just bought a RS200 to replace my R7800

Interesting ... I've just bought a RS200 to replace my R7800 and I get a very similar problem.

I find everything connected to the router loses internet connection but I can still ping the router 192.168.1.1 (same as you)

All the router lights stay lit but none of them are flashing showing that there is no WiFi, Internet or wired traffic.

It stays in this state for 5 minutes then it reboots itself ... ie. all the white lights go out, the power light turned orange and the router boots. After the normal boot time all the lights come back on and all my devices can access the internet again.

I have found a way to 100% recreate the problem. All I need to do is run my BroadBandSpeedChecker App on my phone. This is the Android App version of http://broadbandspeedchecker.co.uk which does a WiFi speed check followed by a Download/Upload speed check. When I start the WiFi check it lasts less than a second before the RS200 is hung.

 I've opened a support case which has been escalated twice, currently awaiting a call from Level 2 support