@Kevin_Z 

By "investigating" you mean asking me questions via email that I already answered in this topic? And not answering to my questions how can I revert this crap router and get my money back? Because I can simple imagine what will happen if I go on warranty to distributor.

I'm not only tired but I'm also really angry on this.

I found something, that makes perfect sense for me (but this is theory for now).

In iOS 14 they introduced something called „privacy mac address”. It means, that every time you connect to the router you have different mac address. If you have bad implementation of DHCP and long lease time (I have 2880 minutes) you can reach limit of your IP pool (i have only 99 numbers on DHCP and many of them are used actively).

When I was on beta version I have only two devices with that functionality. But for now most of my home apple-devices (iPhones and iPads) use this. So when I’m moving around my home I can generate different mac address each time when I’m on C9 wifi area. And this could cause exhaust of free IP addresses.

For now I will be testing it by disabling this feature on all my devices, decreasing lease time on DHCP to 120 minutes (minimum level) AND extending rang of IP addresses to 149 addresses. 

@dmk 

Funny you should mention this. I stumbled across this IOS 'feature' this morning when playing around with 'Connection Alerts' in the Tether App and noticed ios devices appearing twice with different MAC Addresses which was quite strange. Then started trying to think when I and other family members performed the IOS 14 upgrade on devices and had a feeling it was around 2 weeks ago. Haven't disabled yet but guess could be relate since so many people and routers impacted. I'm in Australia but suspect others with this issue are spread across the globe.

Be interested if any thoughts from TP Link.

@Dmk

Any luck yet ? I have also recently upgraded to ios 14 on my devices and come to think about it, that's when it started. But in the admin i do not see multiple mac addresses. 
 

Nope. After few hours router restarted again. So this is not connected with mac address and DHCP.

Recently polish Tp-Link contacted me and offerd to replace my Archer C9 by.... A9. It's crazy - I paid for 4core-s CPU, lot of RAM (in router), 2 USB ports (one 3.0), TimeMachine backups and more and they are offering me to replace it with something much cheaper and much worse.

If they know that problem is real and is inside software, and they already started offering something like that and don't want give money back, the should replace it with highest model covered by gold to shut up this discussion...

@dmk 

At least they offered you something. TP Link Sweden who i Contacted have still not replied back to my request even though its been 6 days..... 

 

But this offer is worst than no offer. I can go and buy this router for half price of C9 in any moment. In fact I'm getting more and more angry because when device is working it's working brilliant - 600Mbps up/down wirelessly and 1/1Gbps via LAN is far good enough. My network infrastructure is good enough for me now. I can replace it at any moment with mesh routers (definitely not from tp-link), but it's not a point now. I invested to have all devices from one company for good cooperation reasons and it's not working. This is real problem. And even on warrenty nobody can do nothing.

Shame on you tp-link.

@swuggmaister I am having the same issue. And I am in Sweden using Telenor/Bredbandsbolaget via Fiber. Actually bought the C9 from Kjell & Co a few weeks ago. It randomly restarts and in the log it looks like this:

2020-10-20 06:06:26 QoS INFO [8876] Service start
2020-10-20 06:06:26 QoS INFO [8876] Function disabled
2020-10-20 06:06:26 QoS INFO [8876] Service stop
 

I have tried the reset button and also upgrade firmware, but same issue. 

It is like the router is perhaps stressed by a DDOS of some kind that makes it restart as the resets are totally random.

TP Please help us!!!

Support stopped responding to me, no support at all for now.