Hi,
I have setup Freeradius with a custom developed PHP/MySQL based fronted for Freeradius. Mikrotik is using freeradius for PPP based authentication.
Freeradius is configured with very basic "radcheck" and "radgroupreply" attributes.
The issue is that there is a specific Wireless routers which when connected using username/password from radius creates issue in resolving DNS (not even connecting to local DNS). What happens in this case is that the client connected to the wireless router is not even able to perform simple nslookup query. DNS is on different network than that of the client. Routes are being pushed using DHCP. In this case if I set primary DNS to be the IP of the Mikrotik router things work fine.
Example. client network=10.0.1.0/24, DNS Server=192.168.100.2,192.168.100.3, Mikrotik IP=172.16.0.2
Things work fine if I set DNS to be 172.16.0.2 (which is not the main DNS Server).
The same wireless router when connected using username/password created in Mikrotik PPP Secret section works fine.
This is happening with only D-Link (dir-600) wireless routers.
I have tested linksys, tp-link, tenda and few other brands which work perfectly fine in both scenarios.
More details can be provided.