There seems to be confusion on everyones part back and forth. Here is my notes after testing thoroughly, same network, same ISP same set of AP's;
UNLEASHED TESTING NOTES:
R500/R600:
200.7 - Had the iPerf3, Ookla and Unifi Speedtests significantly Better. All average around 400-500mbps up/down. Speedflex barely works and when it does the throughput shows 100mbps (+/-20) which I am certain is inaccurate.
R500/R600:
200.6 - Had the iPerf3, Ookla and Unifi Speedtests somewhat worse than 200.7. All average around 300-400mbps up/down. Speedflex actually worked better and the throughput was around 150mbps (+/-20)
R500/R600:
200.5 - Had the iPerf3, Ookla and Unifi Speedtests way worse than 200.6. All average around 200-300mbps up/down. Speedflex actually worked best and the throughput was around 300mbps (+/-20) which seems 200.5 Speedflex still worked.
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R710/R610:
200.8 - Had the iPerf3, Ookla and Unifi Speedtests at worst results. All average around 80-100mbps down and around 30-40mbps up, huge cut on up speed for some reason. Could not get speedflex to work.
R710/R610:
200.7 - Had the iPerf3, Ookla and Unifi Speedtests a bit better than 200.8. All average around 200-300mbps up/down. Could not get speedflex to work.
R710/R610:
200.6 - Had the iPerf3, Ookla and Unifi Speedtests at it's best. All average around 500-700mbps up/down. Speedflex actually worked and the throughput was around 300mbps down and 600 up (+/-20)
R710/R610:
200.5 - Did not test, this FW kills the SECOND LAN port which I needed to use so I did not bother testing. I presume should be same or slightly better than 200.6
I think SpeedFlex is not a good tool. Maybe it's good to check AP to AP speeds. Because every time I tried AP to AP speedflex, always get a 1.3Gbps up/down between ap's. Client side testing does not stay within range of other tests mentioned above.
Also, whoever said enabling mesh, and/or arp filtering helped, it did not. I extensively tested and reset a bunch of times, if anything, arp filtering made it slower. Enabled mesh did absolutely nothing on my bench units.