This device introduces duplicates to my local WiFi network and packet loss to the primary 2.4GHz and 5GHz SSIDs.

I have reset, reconfigured and rebooted the TL-WA854RE several times.

The Tether app (on iOS) connects, then loses connection - again and again. The URL http://tplinkrepeater.net/ also doesn't work, no matter which SSID I'm on.

I have tried using both _EXT and the primary SSID. Both appear to work but . . .

I've never seen duplicates before. Here's a ping snippet after Ctrl-C:

1856 packets transmitted, 1785 packets received, +8 duplicates, 3.8% packet loss
round-trip min/avg/max/stddev = 19.509/49.374/759.165/64.432 ms

And the duplicates look like this (in context):
64 bytes from 23.42.9.252: icmp_seq=1832 ttl=54 time=366.436 ms
64 bytes from 23.42.9.252: icmp_seq=1833 ttl=54 time=36.731 ms
64 bytes from 23.42.9.252: icmp_seq=1833 ttl=54 time=168.893 ms (DUP!)
64 bytes from 23.42.9.252: icmp_seq=1834 ttl=54 time=38.386 ms
64 bytes from 23.42.9.252: icmp_seq=1835 ttl=54 time=202.747 ms

When I unplug the extender, duplicates and packet loss disappear. Completely. 0%.

After trying to troubleshoot this for a week, I am returning the unit to vendor.