NPS will not add Radius client

I've just installed a fresh copy of NPS on a new 2008 R2 Std server. When I go to add a Radius client, I get "NPS Error: The service being accessed is licensed for a particular number of connections. No more connections can be made to the service at this time because there are already as many connections as the service can accept. (Exception from HRESULT: 0x80070573)".

What do I do? This is the first Radius client I am installing (and the first change to the vanilla NPS since running the role installation wizard) so obviously I have not hit the 50 client max.

Cheers

Ok appear to have found it. Bit poorly documented.

The "Standard" edition of 2003 IAS does not allow you to specify an IP range (e.g. 100.100.100.0/24) as a RADIUS client. 2003 IAS will explicitly tell you what you did wrong if you attempt to do so.

2008 R2 NPS Standard (the 2008 R2 version of IAS) will let you use an IP range as the client and then give you the error above. It appears the 50 client max with standard editions is not judged by the number of entries in your configuration, but by the number of hosts those entries cover. While 2003 just spits the dummy straight away, it looks like 2008 R2 tries to validate the number of hosts you are adding, hits 51, and fails.

Hope this helps someone out there.