So... after all this drama and 200.8.10.3.278 turning out to be stable and fix most of the speed issues, I upgraded one AP over to 200.9.10.4.202 and almost instantly it has reverted back to the subpar speeds seen this thread has been posting on previously.
Why is this happening?
Without even going into major details, simple Speedtest.net in 200.8.10 yielded 448Mbps/524Mbps (symmetrical 500Mbps circuit) and on 200.9x it dropped back to 329Mbps/363Mbps. Putting back the original firmware and restoring the conf on it instantly brought the speeds back to what we have been experiencing with the 200.8 fix (almost matching the Speedtest before the upgrade).
I sincerely hope this is not a repeat of the whole 200.6>200.7 drama that started this whole issue years ago. Is anyone else seeing these speed issues with the new firmware (that I believe was being touted as the new fix for all platforms that has speed issues that 200.8x didn’t fix earlier this year).