I have 2 iMacs connected to an Airport Extreme via WiFi. Both have DHCP reservations in the router, and connect to it using DHCP with manual IP. Both are able to connect initially, with the correct IP Address.
Problem is: When either of these machines are brought out of sleep mode a message appears stating the IP address I've assigned to that machine is in use by another.
AirPort Extreme Base Station, Mac OS X (10.7.3)
It would be unnecesary to use both a DHCP reservation AND DHCP with a Manual IP address to assign an IP to a network client. I would suggest that you use one or the other. My recommendation would be to use the DHCP reservation and configure the Macs to use: Using DHCP
Thanks for the advice. I've done as you recommended, however I continue to have the same problem. It seems like it's a timing issue on the DHCP lease, I turned it down from 2 days to 1 hour and the problem is happening much more frequently as expected.
My Setup:
closed network that auto assigns 10.0.1.50 to 10.0.1.200
reserved IPs below 10.0.1.50
router mode: DHCP and NAT
guest network
Maybe it has something to do with the network being hidden?
Ok, if you are using the DHCP Reservation feature of the AirPort Utility to assign reserved IPs below 10.0.1.50 AND have the DHCP scope set to .50 and above, may be the reason that this is not working. The DHCP Reservation feature was meant to reserve an IP within the DHCP scope.
For example, a "correct" DHCP Reservation would be any IP in the .50 to .200 scope that you set. The DHCP service would know to provide these reserved IP from the scope pool to network clients by the MAC address. If you really want to assign static IP addresses to client below .50, then you will want to configure each client for a static IP address.
Tesserax FTW. Indeed this was the problem, when the DHCP Reservations are within the scope the error message ceases to appear.
The issue reared it's ugly head again, after resetting the router to default settings and getting a fresh start I was able to track it down to a wifi based "DECA Filter". I didn't even realize the DirecTV installer had put it in. As soon as I unplugged the DECA box my whole network came back to life. I guess it was also trying to assign IP addresses over coax, so it turned out to be a case of too many cooks in the kitchen.
Thanks DirecTV for charging me to break my network...
Reserved IP Address already in use
