R600 showing AP disconnected after downgrading firmware from 200.7.10 to 200.6.10?

unknown

I recently got two used R600 units and the first thing I did was upgrade them to the latest Unleashed firmware 200.7.10.202.118. I was curious about the speeds I was getting through iPerf and Speedflex and after doing some reading it seems that it's been a known issue and I tried to resolve it by downgrading the firmware. 

The issue that I have now is that both access points show disconnected when they're on 200.6.10.1.308 and 200.6.10.1.310. It doesn't matter if I set them up individually or together or do a factory reset after upgrading/downgrading the firmware. When I go back to 200.7.10.202.118 everything works fine. 

Speaking of speeds, what should Speedflex be averaging in the AP to Client speed test on a mobile phone (2x2 antenna, 866 Mbps link speed, -26 dBm, 5 GHz) and AP to AP speed test?