Disconnect idle user

Hi, I am using pppd on linux nas. The client has connected, then after some time freeradius server has disappered on the network because of connection issue. The user disconnected when it was still down. Then, after freeradius came up the user wasn't able to login anymore because of simultaneous login check with error 691 on windows. Radius was reporting Reply-Message := "\r\nYou are already logged in - access denied\r\n\n" How to make radius stop thinking the user is connected (like if no Acct-Interim-Update messages received in specified time).