The radius dropout reasons mean :
unknown(Termination by server side (NAS) Modem) -- no real definitive answer to this one as it can say this when EU switches router off but can be sometimes hardware issues.
unknown(Administrative reset) - there has been a profile change in terms of speed
static IP(User request) - the radius server has deemed the drop was a 'user request' but this again doesn't necessarily mean the end user has done this as it can be because the router has dropped the connection.
In summary don't read too much into them.