@Oddris The 210's do not have to be in the same subnet as the rest of the network.  I would suggest setting the AP to 192.168.0.250 and the Client to 192.168.0.249.  If you should need to reset one of the 210's, they will default to 0.254.  Once this is done, the PC you plug into the LAN side of the poe injector that feeds the Client should receive an IP address in the router's subnet.  My advice: set them up in your office before installation and make sure this scenario works.  Plug a laptop with a static IP of 192.168.0.10 into the lan side of the 210 that will be your AP.  Connect the 210 that will be your AP to the injector and log into it.  Go to the quick setup tab and set it to Access Point, set the IP to 192.168.0.250, give it an SSID and password, and save your work.  Keep that running and set up your client 210 by selecting Client under the quick setup tab.  Set your IP to 0.249, ckick on survey when prompted, lock it to the SSID you created when setting up the AP, and save your work.  Now you can connect the LAN side of the AP to your router, set your laptop back to dynamic, and you should have the results you're looking for.

Hope this helps