@TimPetro 

Thanks, I will definitely keep these device brands/names in mind, as I plan to keep my Deco mesh. My home network is in different stage than most people have, who are writing in this forum. I am only now getting into IoT, most of my home devices are Windows servers, desktops, laptops and tablets, Android smartphones and smart TVs, Roku-type appliances. They do behave, most of the time. :)

Which means, if I'll get IoT device that does not work with my WiFi mesh, I'll return it back and look for a different brand, instead of being forced to replace mesh. Still better to know in advance what not to try.

I would not tolerate that mess you described either. Hopefully it was all Deco's fault, and not Deco behaving like a canary in the coal mine. Meaning, that you might have an underlying issue in your network, or with your ISP router, that stayed dormant till it collided with Deco mesh.

i had this same issue happen on a laptop.. i didnt capture the packets with wireshark, but i did release and renew several times and kept getting the same IP over and over.... left it.. came back several times over the hour.. still same thing. So even if the DHCP is 1 minute... the Win10 laptop issue proves that my X20's DHCP stayed up and running and didn't have it 'temporarily' running as TPLINK mentioned.

Next time, if you got in this situation and don't have any good networking tools in your disposal, just use ipconfig /all on Win10 laptop, it'll report you DHCP lease time and other useful stuff. Below is an example screenshot from my network when I was running tests. 

On my network:

Network default gateway, DHCP and DNS IP: 192.168.0.1.

DHCP range starts from 192.168.0.10.

I pull out power cable from ISP router, and after few moments, when Main Deco M9 Plus with IP 192.168.0.131 realizes Internet is lost and takes over, here is what I've got on my Win10 wired desktop:

As you can see, Main Deco declares itself default gateway (instead of 192.168.0.1), declares itself DHCP server (obviously, or we won't be discussing this), and adds itself to the list of DNS servers.

It also gives one minute DHCP IP lease to Win10 desktop PC, as seen from Lease Obtained and Lease Expired.

When I power back on ISP router and it takes over, Main Deco goes back to what it should do (Access Point), and without anything done on my part for network or computer, my Win10 desktop returns to this:

My ISP router is configured with DHCP lease time of two weeks.

@Alexandre. 

I want to be fair to TP-link.. i found the DHCP issue and being a 30 veteran in information systems... teaching for Cisco, microsoft and vmware.. i cant believe i missed the issue. I used wireshark to capture the DHCP discover, offer, req and ack/nak packets and found that when i 'reset' the unit to try to get the satalite's paired to the main.. i wiped out the VLAN (802.1q) setting for the guest network. When that was lost, it allowed my Cisco ASA to send DHCP from its guest VLAN on the main VLAN. Alexadre,,,, thanks for the tip of 'confirming' who i think the DHCP server was. You can see in the capture below.. it was my Cisco ASA. That beiing said. i still have the same issues with the units going offline, but the DHCP issue is not the fault of the DECO. THe new orbi's are coming tomorrow.. i'll post how well they work. Now. .i'll probably stay up and fix all my home stuff getting them on the same network now that i fixed the issue with the VLANS.