There's two particularly troublesome spots in the auto-generated nav mesh on 2fort. This is an easy fix and would help bots navigate correctly for a better user experience.
Fixing the issue with the stairs is as simple as removing the affected areas of the mesh (or marking them as avoid areas):
As for the grate, here's how I fixed it. First, here's what it looks like now:
You can disconnect all vertical connections in this area, and then split the yellow square into three segments:
Then it's as simple as connecting the pathways to the middle segment:
Fixing the issue with the stairs is as simple as removing the affected areas of the mesh (or marking them as avoid areas):
As for the grate, here's how I fixed it. First, here's what it looks like now: