With IPHost Network Monitor you can run simple snmp requests against a D-Link device in your network.
swRadiusDeadTime
Switch Radius Dead Time
1.3.6.1.4.1.171.12.3.2.1
Specifies the number of minutes a RADIUS server, which is not responding to authentication requests, is considered unavailable and is passed over by further requests for RADIUS authentication.
Back to AUTH-MIB MIB page.
IPHost Network monitor allows you to monitor swRadiusDeadTime on D-Link device via the SNMP protocol. Download IPHost Network Monitor (500 monitors for 30 days, 50 monitors free forever) to start monitoring D-Link routers right now.