I've solved it with huntgroups with individual client IP's but I need to do it by subnet.

I thought the following would work but it didn't.

/etc/raddb/huntgroups
hunt1        NAS-IP-Address =~ /^192\.168\.(89|90|91)\..*$/


This appears to have been fixed by putting quotes around the regex in place of the "/"

hunt1        NAS-IP-Address =~ "^192\.168\.(89|90|91)\..*$"