WiFi frequency planning across a multi-story multi-building site gets real hairy.
You have 20/40/80 GHz channels and extension channels on 2.4 GHz and 5 GHz, and you've got to try to minimise the overlap, and where you can't, you have to exploit radio barriers in the buildings (concrete) and the distances between buildings and floors to create isolation.
It's a giant puzzle. It would be a nightmare if I wasn't such a huge nerd who loved such challenges.