New install, on my R710 Unleashed with the latest firmware. I have a blinking Green PWR LED, the manual seems to indicate the device did not get a routable IP but that's not the case.
in fact, connected users are able to browse the LAN and the Internet just fine and I'm able to login to the AP via its IP. I've statically assigned a DHCP lease to the R710 and also manually configured an IP and the same blinking LED persists.
I encountered the same issue a few months back after upgrading to v18.104.22.168.186. I logged a support case for it and was advised that it might be fixed in a future release, but in the meantime it could be worked around by using a static IP. Here's a thread on the subject: