Looking for some help with an odd problem on my home network.
I have an Archer MR500 providing internet, DHCP and WiFi to the house. A linked SG106PE provides wired Ethernet and, to support the part of the house that the MR500 doesn't reach, I added a TL-WA855RE extender. This runs as an Extender with its own SSID, DHCP is turned off on this device.

This setup works perfectly most of the time but, about once per fortnight (on average), the extender seems to go quite feral.
 

Here's what happens:

1. Devices connected to the Archer router (WiFi or wired) disconnect from the network. This hits both static and dynamic IPs
2. Trying to force the connection with a restart or release and renew lease, just gets a local APIPA machine IP
3. Devices connected to the extender SSID continue to work perfectly
4. An IP scan on the network show it holding multiple IP addresses against its MAC address (including that of the MR500)
5. A check of the event log on a wired connection shows the following error message at the point of being kicked off:
   The system detected an address conflict for IP address 0.0.0.0 with the system having network hardware address F2-A7-31-0C-0C-94. Network operations on this system may be disrupted as a result.

That MAC address, ending OC-94 is the extender.

The workaround is to power off the extender, wait a while for everything to connect again and then power-up the extender. Everything then works normally for another week or so before it all happens again.

Any suggestions? I'm considering dumping the thing and changing for a mesh unit, but there's an element of pride here, I'm no network engineer but I am supposed to understand this stuff...