@tonyholdgate 

To reboot Main Deco through Deco app, see How can I reset or reboot my Deco Whole-Home Wi-Fi System?

Do you have anything connected to the second port of Main Deco? If answer is "yes," check this forum for WAL/LAN autosensing discussions. 

the connection dropped again some 5 hours later.This time I hard power cycled the router unit after confirming the internet was still connected to prove the issue is routing based. Note on both occasions the unit stopped creating logs some hours before each stoppage. Wifi continues to work each time. Nothing connected to the second unit. I can see there has been no new firmware for sometime so these are going back to amazon as I need a reliable solution

so I'm going to try setting the connection to the ISP as static as I pay for a static address. This should not be necessary but I'm prepared to give it a try as the wifi performance has been outstanding.

It's really obvious that the firmware for these units is unfinished. There are spelling mistakes all through the logs and even one of the log titles. The logs are not much use and show no cause for the main unit stopping routing.  It's been a while since there has been a firmware release and this makes these units seem abandoned. No debug mode and no sign of a watchdog is a very bad thing

I'll give this one last chance as I still have 13 days left on my 30 day no fuss return. In the mean time tplink get onto the firmware and sort it out. We need a proper watchdog  checking internet connection that restarts the router process if it drops . More importantly I suspect there is a memory leak which is why a warm boot is a temporary fix

  @tonyholdgate logs attached from first fail. Unit failed at 22:05pm- logs stopped at 19:25 approx

Note that the unit still displayed the IP from the ISP and responded to both the app and web admin page correctly.

I've found software X68_1.0_en_1.0.5_Build_20220317_Rel. 11446_EU_JP_US_up.zip which apparently  is newer than the  1.0.4 Build 20210519 Rel. 36755 I have installed.Updated now

  @David-TP Screen shot attached - internet was out yet IP still displayed on the webpage.

ISP is Aussie Broadband. CGNAT exempt and  Static IP  (Dynamic IP setting still required)

Already tried  Google DNS- no change.

New firmware is no more stable that the old- exactly 24 Hours since the last crash and thats just not going to work for me. returning for a refund

 I've had support set up logs to catch the now 36 hour crashes- no luck as the unit stops producing logs about 3 hours before it  goes down. I've reached the end of the road on this one. Considered the x90's but its the same underlying architecture and I don't have the speed from my ISP to justify it. Packing them up and returning today. Big shame as the coverage was great