Just made my openwrt router my main router and while setting up wifi there’s a few things i’m not familiar with. I have A 2 Band router an AC and N mode. I’m not sure what the settings are to use on these especially what width, if i should turn on 802.11r fast transition and 802.11b legacy rates.
If it's your only router that supports 802.11r) then you don't need to worry about enabling that.
If you don't have legacy count devices then you don't have to worry about it either.
Start with 20 Mhz on the 2.4 GHz band, and 80 MHz on the 5 GHz band.