Problem:
The situation is, that all computerobjects are stored beneath the same OU. There is a subnet definition for subnets one for each server. The school has its dhcp server split into these 2 subnets.
Investigation:
That all computerobjects are stored beneath the OU is the default position for client objects, and they cannot be moved.
Move dhcp/host not allowed
Solution:
The crux is, where the policy definition is linked to.
You should not have any dhcp policy linked to the ou itself, but exclusively at the subdomaindefinition.