Most higher modulation levels cannot use 29 or 30dBm TX power. Ideally, you don’t want to be running really low modulation levels on these links. It would be better for you to use a smaller channel width to increase your PSD which in turn increases your chances of achieving higher modulation rates. You also will probably have better stability and overall performance if you stick to the newest firmware release. Going backwards in firmware to achieve 1dBm of power that only benefits the slowest modulation levels is not a good idea. If you need more gain then use a larger dish. This will help with all modulation levels.
If you’d like to see each modulation level’s transmit power at each channel width, take a look at this table here: