NETGEAR C3700 allowing a 'Denial of Service' attack?

Often early in the morning I experience hangs while using Safari on my Macs and iPads.  The hang doesn't last more than 5 minutes,  but I've discovered that during that time the router admin 'Attached Devices' page  shows a suspicious IP address (81.0.229.0) assigned to one of my iPad devices.

This IP also shows up in the 'Logs' page associated with a DoS attack.

A 'whois' shows the IP belonging to JanigaLabs-CZ.

I have screen prints if anyone thinks they can help.