Looks like when you bridge the Raspberry Pi it will use the same MAC address for both the bridged connection and the Wifi connection. I have tried setting it manually with no luck. You cannot set a rule for the MAC on the AP because of this issue, that is why I had to set it on the Opensprinkler itself. If you look at your AP you will see it flop between the ip address connected to the NIC and the ip address connected to the Wifi connection itself. When I hard-wire the Opensprinkler it functions with no issue. For some weird reason the Opensprinkler locks up hard with this configuration.