successful authentication (peap and TTLS), but internet access that for 5 seconds

[Sautron Nick]

Hello everyone,
I have a problem with my freeradius server (or maybe switch), 

the problem is that : 

   I connected a customer on a switch port (Cisco 2940) configured 802.1X
 Authentication is successful, but I have access to the internet that for 5 seconds and after nothing.

 I wonder if there is no configuration to avoid this kind of problem.
Best regards
S.Nick