So the Wifi works for you as-is with the image? If you previously uploaded the calibration data from this thread you can compare the two mtd partitions (fakeradio and radio) and see if they are different. If you don’t see a fakeradio partition in /proc/mtd then you somehow don’t have my kernel build.
Re the faster speed, if you see this in the web interface, this is primarily because I am using OpenSSL instead of mbedtls. It has some pitfalls though, see Debugging memory use / OOM crashes for what I am facing.
I haven’t looked at the wifi power options with the original radio yet. I see 23 dbm for 5 ghz wifi, and I think that was the same with the radio image from this forum. 2.4 ghz goes up to 19 dbm, and I believe it was 20 before. That might explain why the 2.4 ghz wifi works better.
I built the kernel with a hack to enable DFS channels I described in this thread earlier, but I am not actually using that - I am running the 5 ghz wifi on channel 36.