That link describes, but does not explain, what the benefits are, and how they might be obtained 😢
5Ghz Is faster than, but does not have the penetration of, 2.4Ghz
2.4Ghz is slower than, but penetrates further than, 5Ghz
And it’s no good just splitting the bands; you then have to revisit each affected device, and ensure it’s on the optimum band for what you need.
So a device that isn’t getting good coverage, and isn’t already on 2.4Ghz, should be moved to that band. As slow(er) coverage is better than no coverage.
And devices that you want to get faster WiFi with, and aren’t already on 5Ghz, should be moved to that band; but check that you still get the coverage you need, as that may be a gotcha.
Alternatively, you might like to look at a WiFi mesh system, like Amazon’s eero, say, to bolster what the Now router can achieve.