I did additional tests about WPA2 Enterprise problem with WRT3200ACM (systematic disconnection after one hour) :
- tried several older 88W8964 firmwares (9.3.2.6, 9.3.2.5), same symptoms.
- tried with stock Linksys firmware (1.0.8.198828_prod), same symptoms.
I will try with a different RADIUS server to see if that makes a difference. Today I am using the RADIUS service from a Synology NAS, which has been working fine for several years on my WRT1200AC.
I will report about the results.
Edit : Same problem. My Radius server (FreeRADIUS running on pfSense) is showing a successful re-authentication, the Wifi client seems to remain connected Wifi-wise, but is loses its IP address, and is unable to renew it (tried manually).
My conclusion is that WRT3200ACM cannot handle WPA2 Enterprise properly 
Other reports of the problem here.
Workaround : in fact adding option eap_reauth_period '0' do seem to fix the problem 