Archer C7 router crash

I am having the same problem as deboralbasso. My archer C7 V2 worked flawlessly for almost a year, and is now dropping connections, frequently, at least once a day, and I have to reboot the modem to get it working again. Here are the details:

Model: TP-LINK AC 1750 dual band Gigabit router

Firmware Version:	3.15.1 Build 160719 Rel.57530n
Hardware Version:	Archer C7 v2 00000000

When it dies, here are the symptoms I see:
1) All wireless connections including wired connections are dropped.
2) The modem stops broadcasting SSID in both bands.
3) Only of of the two LEDs on console (2.4) flashes on the modem, other one is not flashing.
4) At times, I do see slightly different behavior - The SSID is broadcasting, but wireless clients cannot connect, and they report password is not correct (but the password was correct)

Here are all the things I tried
1) Disabling 5.4 GB band 
2) upgrade firmware to latest from support web site
3) factory reset the modem and reconfigure

But none of them have helped so far.
I and tech savvy and can provide any system logs for a support engineer to troubleshoot, please let me know how to collect them from modem. I looked through System tools -> System logs but there is not anything in there that seems to be of significance there. Please provide detailed instructions on any diagnostics you would like me to collect.