Thanks for replying

In /var/lib/rrd I have eth0.rrd, eth1.rrd and eth2.rrd, all of which are 55Kb. After a lot of snooping on the router, I've found image files at /share/www/rrd/, but when I go to
http://192.168.1.1/rrd/, nothing is displayed, but it looks as though the router is intercepting it somehow. In the source, there's what appears to be JavaScript for managing the default settings.