No more issues, its been rock solid maintained connection for 55 days currently, never had any more random disconnects. Not sure if the firmware upgrade caused those disconnects or whether it was just co incedence and my isp was having issues that day. I downgraded the firmware and swapped the Ethernet cable between cable modem and the router and its been fine since then.
The only minor issue I have is that chrome web browser on m nexus 7 tablet doesn't work properly with the web management interface of the router. That's probably a chrome issue though works fine on Firefox. If DD WRT was available for this router it would be an even better buy.