Hello, I bought an Archer A6 router 1 month ago, and recently I'm having insane packet loss on WI-FI connected devices. There are 6-7 devices connected to my router, only 1 device is connected by ethernet cable.

Pinging google.com.

I tried:

• Resetting my router,
• Factory resetting my router,
• Disabling NAT,
• Using QoS,
• Enabling/Disabling MU-MIMO feature,
• Reinstalling my network card drivers.

I can't connect my laptop with an ethernet cable. I don't know what to do, is it hardware problem or anything else?

Edit:
I did diagnostic test on tplinkwifi.net, here are the results:
 

PING google.com (216.58.208.206): 64 data bytes
Reply from 216.58.208.206:  bytes=64  ttl=120  seq=1  time=17.585 ms
Reply from 216.58.208.206:  bytes=64  ttl=120  seq=2  time=10.791 ms
Reply from 216.58.208.206:  bytes=64  ttl=120  seq=3  time=24.076 ms
Reply from 216.58.208.206:  bytes=64  ttl=120  seq=4  time=57.638 ms
Reply from 216.58.208.206:  bytes=64  ttl=120  seq=5  time=28.908 ms
Reply from 216.58.208.206:  bytes=64  ttl=120  seq=6  time=52.569 ms
Reply from 216.58.208.206:  bytes=64  ttl=120  seq=7  time=43.374 ms
Reply from 216.58.208.206:  bytes=64  ttl=120  seq=8  time=21.225 ms
Reply from 216.58.208.206:  bytes=64  ttl=120  seq=9  time=11.529 ms
Reply from 216.58.208.206:  bytes=64  ttl=120  seq=10  time=9.925 ms
Reply from 216.58.208.206:  bytes=64  ttl=120  seq=11  time=26.989 ms
Reply from 216.58.208.206:  bytes=64  ttl=120  seq=12  time=18.692 ms
Reply from 216.58.208.206:  bytes=64  ttl=120  seq=13  time=12.374 ms
Reply from 216.58.208.206:  bytes=64  ttl=120  seq=14  time=13.373 ms
Reply from 216.58.208.206:  bytes=64  ttl=120  seq=15  time=10.465 ms
Reply from 216.58.208.206:  bytes=64  ttl=120  seq=16  time=34.965 ms
Reply from 216.58.208.206:  bytes=64  ttl=120  seq=17  time=21.598 ms
Reply from 216.58.208.206:  bytes=64  ttl=120  seq=18  time=8.018 ms
Reply from 216.58.208.206:  bytes=64  ttl=120  seq=19  time=21.569 ms
Reply from 216.58.208.206:  bytes=64  ttl=120  seq=20  time=15.053 ms
Reply from 216.58.208.206:  bytes=64  ttl=120  seq=21  time=15.249 ms
Reply from 216.58.208.206:  bytes=64  ttl=120  seq=22  time=10.829 ms
Reply from 216.58.208.206:  bytes=64  ttl=120  seq=23  time=11.749 ms
Reply from 216.58.208.206:  bytes=64  ttl=120  seq=24  time=25.513 ms
Reply from 216.58.208.206:  bytes=64  ttl=120  seq=25  time=9.314 ms
Reply from 216.58.208.206:  bytes=64  ttl=120  seq=26  time=14.762 ms
Reply from 216.58.208.206:  bytes=64  ttl=120  seq=27  time=93.621 ms
Reply from 216.58.208.206:  bytes=64  ttl=120  seq=28  time=30.418 ms
Reply from 216.58.208.206:  bytes=64  ttl=120  seq=29  time=19.788 ms
Reply from 216.58.208.206:  bytes=64  ttl=120  seq=30  time=16.857 ms
Reply from 216.58.208.206:  bytes=64  ttl=120  seq=31  time=17.400 ms
Reply from 216.58.208.206:  bytes=64  ttl=120  seq=32  time=28.247 ms
Reply from 216.58.208.206:  bytes=64  ttl=120  seq=33  time=26.591 ms
Reply from 216.58.208.206:  bytes=64  ttl=120  seq=34  time=7.586 ms
Reply from 216.58.208.206:  bytes=64  ttl=120  seq=35  time=38.522 ms
Reply from 216.58.208.206:  bytes=64  ttl=120  seq=36  time=11.171 ms
Reply from 216.58.208.206:  bytes=64  ttl=120  seq=37  time=7.775 ms
Reply from 216.58.208.206:  bytes=64  ttl=120  seq=38  time=8.694 ms
Reply from 216.58.208.206:  bytes=64  ttl=120  seq=39  time=12.686 ms
Reply from 216.58.208.206:  bytes=64  ttl=120  seq=40  time=29.952 ms
Reply from 216.58.208.206:  bytes=64  ttl=120  seq=41  time=22.345 ms
Reply from 216.58.208.206:  bytes=64  ttl=120  seq=42  time=15.550 ms
Reply from 216.58.208.206:  bytes=64  ttl=120  seq=43  time=9.884 ms
Reply from 216.58.208.206:  bytes=64  ttl=120  seq=44  time=37.874 ms
Reply from 216.58.208.206:  bytes=64  ttl=120  seq=45  time=13.860 ms
Reply from 216.58.208.206:  bytes=64  ttl=120  seq=46  time=37.143 ms
Reply from 216.58.208.206:  bytes=64  ttl=120  seq=47  time=32.513 ms
Reply from 216.58.208.206:  bytes=64  ttl=120  seq=48  time=21.311 ms
Reply from 216.58.208.206:  bytes=64  ttl=120  seq=49  time=28.139 ms
Reply from 216.58.208.206:  bytes=64  ttl=120  seq=50  time=8.368 ms

--- Ping Statistic "google.com" ---
Packets: Sent=50, Received=50, Lost=0 (0.00% loss)
Round-trip min/avg/max = 7.586/22.489/93.621 ms

Packet loss happens when CPU Usage skyrockets to even 30%.