I have Archer VR600 and TL-WA854RE Range Extender. 

My Wireless Network very slow when TL-WA854RE connected to VR600 over wifi. I wanted to learn what is the problem. I pinged from linux client and i saw this result. (linux client connected to network over wired network). 

VR600 IP Address : 10.0.0.1

TL-WA854RE IP Address : 10.0.0.2 Connected to Router over Wifi

64 bytes from 10.0.0.2: icmp_seq=1 ttl=64 time=811 ms
64 bytes from 10.0.0.2: icmp_seq=2 ttl=64 time=652 ms(DUP!)
64 bytes from 10.0.0.2: icmp_seq=3 ttl=64 time=712 ms (DUP!)
64 bytes from 10.0.0.2: icmp_seq=4 ttl=64 time=611 ms
64 bytes from 10.0.0.2: icmp_seq=5 ttl=64 time=741 ms (DUP!)
64 bytes from 10.0.0.2: icmp_seq=6 ttl=64 time=956 ms (DUP!)

64 bytes from 10.0.0.1: icmp_seq=1 ttl=64 time=612 ms
64 bytes from 10.0.0.1: icmp_seq=2 ttl=64 time=633 ms
64 bytes from 10.0.0.1: icmp_seq=3 ttl=64 time=515 ms
64 bytes from 10.0.0.1: icmp_seq=4 ttl=64 time=698 ms
64 bytes from 10.0.0.1: icmp_seq=5 ttl=64 time=712 ms

And i saw that Wired Network interface and 2.4 GHz network interface have same MAC ID. (5 GHz has different MAC Address

Some users told that DUP is duplicate packet on your network. I wanted to change MAC Adrress of wired network interface or wifi. but there are no option for that. 

Is there any solituon for this problem?