SSLVPN authentication breaking

[GuyB]

Hi, Since upgrading to fortios 5.0.4 and later to 5.0.5 we are having SSLVPN authentication problems. We are using radius for authentication but the problem alsu happens with local firewall users. When the fortigate is running for a few days, at some point users can no longer connect to the SSLVPN using the SSLVPN client (latest version but also previous versions). The event log starts to show these errors when this happens : action=authentication status=timed_out reason=" Authentication timed out" msg=" User from x.x.x.x was timed out" The radius servers are Windows 2012 domain controllers with the Windows Network Access and Protection component. This has always worked fine with version 4 of fortios. It is also not a Windows radius problem as other systems are authenticating OK. When the firewall is restarted all is working again.