EX5601-T0 no devices showing on connectivity page

In the router admin web interface I can find no devices listed in the Connectivity section.

192.168.1.1.> Connectivity shows Wired(0) and Wi-Fi(0)

There at least 10, and probably more than 20, devices connected not least the one I'm using to send this message. I know this page used to work but not any more.

I've emptyed the browser cache and re-booted the router but still no devices show.

Many thanks, in advance, to anyone who can help