I am running ver 3.10 on all my MT’s Level 4 licences. I have a Radius server within the same local network. Radius authorises and communicates correctly.
All working fine no unexpected rejects in the Radius status. However after while user logsoff, Radius sees and records this.
Interim Accounting is on and set to 00:30:00.
The hotspot profile has Addresses per mac set at 50 and the idle timeout set at 00:55:00.
The server profile is using Radius via Http-chap and Cookie and cookie lifetime is set to 12:00:00.
Somewhere in between here I get a I get in the log Hotspot1:DHCP host {mac id}/{dhcp assigned address) added. But hey that mac is logged (active user) in and has an ip address already. Confusion reigns. User can get to login but get error message Login Failed: no more sessions allowed.
Then user cant get on internet then calls me. I want peace and quiet. I then have to remove users cookie. delete the active user. and delete any assigned addresses in the DHCP Server.. network..leases.
There are only 12 users in this little network.
any clues on how to get over this. 
Can;t help but notice that the cookie lifetime is 12hrs, yet the idle timeout is 55mins.
Maybe MT gets confused a bit.
I used to get this all the time.
I changed to just MAC or http-chap auth (disable cookie) and now it works OK for me.
Also, customer cannot forget their MAC address either …
Adrian.
Hello fren,
yes, it's user still connected and accounted on your radius.
please recheck 'Keep alive timeout' on your hotspot profile and not set to more, i think better will you set 900s
regards 
Hasbullah.com
the answer seemed to lie in removing Cookie authentication. Nearly 26 hours no more ‘Login Failed: no more sessions allowed’ Happy Bunny at moment. 