I have seen conversations around this in the community but always when using VLAN Tagging. In this simple case, I have this disabled, so there should be no tagging with everything going into the default flat network. The MX64 is acting as the DHCP server with a 192.168.128.0/24 network servicing the 50ish devices at the site.
Every other device works perfectly connecting to the same SSID, but these two devices have a terrible time connecting because (I believe) they cannot get an IP address. In trying to resolve this, I setup both of them to have IP lease reservations, but that hasn't resolved it.
Both of these devices are EcoBee 3 Lite smart thermostats. Does anyone have any idea why these units can get connected and request an IP but then fail with the error above?
At times, the units will get an IP address and they work for a while. But as soon as it tries to renew the IP, everything falls apart again.
You might try turning one off or disconnecting it and see if you have the same issue. You might also try resetting one of the devices, possibly something is being odd on the device keeping an IP it previously had.