Most of the time you want the default, dual-band, which swaps between whichever signal is strongest wherever you are now.
2.4GHz has longer range, better penetration, and is less affected by obstacle occlusion, but is more susceptible to wifi interference in built-up areas. It is more directionally forgiving as well.
Whereas 5.8 GHz has a shorter range, but is much better in commercial or residential areas where there is a lot of nearby WiFi signals present, because so much fewer of them will be in the 5.8 GHz range. But this is more directional, so suffers if your aerials are not aimed at the craft, and is particularly bad if there are walls or trees between you and the craft.
Not sure it's the same on the
M2SE, but on my
M4P that page is quite useful in that it allows you to actually see the interference and signal levels for each band, so in new locations it is a good idea to sit there for a couple of minutes and watch each channel to see how stable each signal is. Really the only time you would want to select one over the other is if you notice consistently bad signal in one range. OR if you are (for example) miles out in the country / middle of nowhere and you KNOW there won't be any other wifi around then you might set it to 2.4GHz only. Probably not worth the effort tho - Dual band is very good at doing the right thing.
