I have some devices such as QNAP NAS drives and a computer that is not part of the domain connected to our network. I have assigned a static IP to these devices. Sometimes I find that the windows DHCP server has assigned one of these IPs to another computer which causes problems. These devices are never switched off, yet somehow the server is assigning these addresses to other machines? The VPN service also sometimes assigns these existing static ips to remote clients which prevents them from connecting to network resources.

I didn't think this should happen. I haven't set a reservation or exclusion in the DHCP server because I didn't think I should have to. There are quite a few statically assigned devices, so that would mean I would have to add all of them to be excluded.

Does anybody have any hints on how I should solve this?