(Modem)/Router that can support USB Disk as NAS

I'm looking to replace my old Speedtouch 585 v6 on an Zen ADSL line with something that I can attach my external USB disk (Hitachi based ioSafe) to.

After research I opted for the HG612/RT-N66U. I managed to unlock the modem ok and got it working. Getting the Asus to connect was a lot of faff but eventually it worked. On attaching the USB Disk the router detected it but I couldn't see it on the network either from my Macbook or an ageing Win 7 laptop.

On talking to Asus support, they suggested upgrading to later firmware than the router could detect (via http://www.asus.com/Networking/RTN66U/HelpDesk_Downl... This was even worse as I ended up with regular wifi dropouts and no improvement in USB disk connectivity. As I couldn't get a resolution with Asus support I gave up and sent the router back to Amazon and got my refund.

So my question to the experts is what to try next. For info, I'm probably looking to upgrade to fibre so something that is future proof is required.

The stock firmware I think is not perfect as a DLNA device, which is probably want you were after, I've not used the USB functions for ages so cannot comment on how they are with the alternate Merlin/Tomato versions.

DLNA even on some dedicated NAS that I've had the pleasure to use has always seemed hit or miss.