@dmk 

You are really stupid. If you might know the solution (which I doubt since this is the third time you wrote this) then you should share it with tp link so they can fix this for all. Why be so egoistic? TP Link have shown interest to help out, if they don't know the issue they cant fix it of course. I think you are being very selfish and saying TP link sucks etc etc is just bad maners. My TP link router has been perfect for 2 years.

My friend, it's not about being stupid or selfish. I offered a lot of my time for debugging to the support, offered logs (custom, not from mgmt area) and full support as from user side. In return I received offer of exchanging my router to low-end models and raillery from polish support, and no response from global support. I'm not a full-time job tester for tplink, and especially not their engineer. I'm owning high-tech company and we never treat our customers like this. Knowledge costs and if someone does not appreciate it, then he is stupid.

PS This is not open-source solution. Every firmware need to be signed to install. This means, that you can not simply modify it and push to the router - even for debugging process. So if they decided to close the software, they need to provide fixes and warranty. If not - go and buy another company routers.

PS2 If your router has been so perfect, what goes wrong? You should be still happy about that. Or not?

@Hacjob 

Hi there. Is  your iPhone on ios14 and did the c9 only start rebooting around the time you upgraded to this version?

I think this issue is related to iOS14 indeed. I switched off the "private address" functionality two days ago and haven't experienced a router restart since.

@Kevin_Z 

Hi , i received an email from R&D with a debug firmware but it said to refer back "to the attached debug instructions"however no instructions are attached. 
 

can you please explain what to do exactly ? I am not that tech savy. 

@Kevin_Z

and all

I thought I was onto something as had avoided any reboots for 3 days. Unfortunately there has been 2 today so far (though very quick, with connectivity resumed in 1-2 mins max) :-(

Since upgrading ios devices to ios14, I had noticed that IOS advised of a "Weak Security" warning for my TP-LINK 2ghz & 5ghz wifi networks because the default C9 wifi security settings seems to result in WPA2-PSK but with TKIP encryption. I didn't think this should have any impact to the C9 but none the less explicitly selected WPA2-PSK with AES encryption and the warnings disappeared from ios14 devices and as above (unfortunately knew it was too good to be true) not a single reboot for 3 days. Alas back to square one and hoping TP-LINK can get this resolved soon.

@Kevin_Z

Hi. As above did not resolve the issue. Though the frequency of reboots reduced, it looks like it could have been a  coincidence or possibly due to lower internet use over the 3 days when the security change was applied.