First a measurement: iperf (do your tests with --parallel 4) achieved over 80 Mbit/s between two dockstars with TL-WN821N v3 interfaces (one in master mode, the other in managed mode, wpa-psk, txpower=20, no bridging at all). Let me explain what I'm trying to do. I should'nt have used the word "bridge" in my previous post, because I didn't mean it as in "interfaceby lemur - Debian