I've just started seeing this error - three times in the last four days. Power cycling the router fixes it every time, but this is a hassle.

I'm using firmware 3.3.5.2_232201 and have been for a little while now.

On BT Broadband and did experience the downtime on Monday. That's all that's changed really.

Oh, I did put in an old D-Link desktop network switch. That couldn't have done it, could it?!

Does any of this help tie down the problem?