I have the same issues with my Archer C1200 V1 too. Recently upgraded my firmware but I doubt if the problem is really solved. I did some research and sifted through the firmware blame comments. Finally, I found a Youtube video of another TPLink Router owner with slightly different issues:

How to fix a rebooting or stuck TP-Link Router W8960N - I wish I knew this earlier!

I guess that insufficient power supply will cause the router to "dim out" and thus causing a restart.
I might try to get a higher amp rating power adaptor instead (2A instead of 1A) and see if the problem will be solved.
Any of you tried using a higher amp P/S adaptor for this router before?

From all other Lowyat forum expert experience, the old series C5/C7 still the best and stable. not sure whether I still can get it...

Hi! I'm a tech noob.
Bought a lot of Wifi Router but still the wifi very slow.
Currently using TP Link TD-W8961N on TM Streamyx 8Mbps.

If use with LAN the line is strong. But with wifi the line is super slow.
Even bought Wifi Extension still not working.

Contacted TM guy but still the problem persists already few years. They even ask us to change router and we already change 3 Wifi Router.. still the same problem!

Anyone can assists? thanks   

Chromecast just kill my C2600, connection dead.
1. off TV (sharp FHD LED TV)
2. re set chromecast (tested x3 times, kill 3 times)
3. re start C2600 ( hidup again without chromecast)
4. WT@#$%^, & wait for update.

i have a problem with my pie wireless. im using t9e. everytime i start my computer, t9e didnt detect and show that i have wireless connection adapter issue or no wireless detected. im using win10 x64. my old tl-wn321g didnt have this issue at all before

I read mixed reviews on this product before purchasing and the poor reviews were the correct ones. The drivers were not compatible with Windows 10. After visiting the manufacturer website and downloading the latest update that was listed as compatible, the new drivers didn’t work. I returned the product and moved on.

Cons: Drivers are horrible, or Microsoft is being, well, Microsoft! I did a fresh install of WIndows 10 1803 yesterday and this thing became completely unstable. Had to downgrade to 1703 and now 1703 is giving me issues. This card always likes to act up when I'm playing a game. I paid good money for this card and most of the time I have to worry whether or not online gaming is going to be an enjoyable experience. TP-Link, Microsoft, get your "stuff" together.

Works fine after I got rid of the Blue Screen. A recent windows update caused this problem...I think. It took me a heckuva long time to debug what was happening to my PC, but it's finally running fine now...after I removed this hardware, and the driver. I had downloaded the latest driver from TP-Link but the issue persists. I'm going to return this item and go back to my LAN cable for now...and return this item. The "new" WIN 10 driver did not solve this issue on my machine

I do see ppl having issues with this car on win10, it could be that those having issues have the 1st revision. the one I received for my son was different rev from the one I had that died 2months ago(maybe my rev 1 card was still good but an update rendered it useless due to some older components. they both use same software so I don't believe that's the issue but you never know.)and rev 1.2 is working great.

Worked fine when I first got it but since fall of last year's update it has stopped working despite contacting the manufacturer(they claim Microsoft has to fix it, Microsoft claims it's a driver issue) So it's a dead card atm.

If you want this to run properly on windows 10 64bit, do not use the manufacturers drivers. With manufacturers drivers, the card would "die slowly" when using all the bandwidth (for example, downloading a 60GB game on steam would stop at the 8GB mark and would only resume if I disabled and enabled WIFI back again). The Archer T9E is a BCM-4360 based card so I strongly advise people to use the Broadcomm BCM-43XX Wireless LAN driver 7.35.333.0 WHQL reference drivers instead (require manual install from Device Manager). Search for "broadcom_wlan_7.35.333.0" on google. These drivers solved all my issues and the card is now working like it should.

TLDR: On Windows 10 64bit avoid manufacturers drivers, search "broadcom_wlan_7.35.333.0" on google and install these instead.

Yes, but it is only N and not AC, and has very basic hardware

Nope, not even close. Click the link on my signature to see list of compatible routers for 300Mbps and other general info.

Sorry noob here..any advice what to buy for single user, 4G LTE modem using prepaid data?

Still a really stable, well tested and well made router from TP-Link.

If you want better performance, get Archer C80 or Archer A9 instead.

Option A
Run the Deco M4 on router mode, it will be on a different IP range different from Router 1. Wi-Fi devices will not have access to devices connected on main router.

Then you can eliminate the need of router 2 and connect them directly to the 2 ports on Deco M4.

Option B
If you run the Deco M4 in AP mode, all Wi-Fi devices will be on the same main network but you will still need the router 2 if you wish to do separation.