Factorio Forums

Please see attachment.

Substations never allow you to walk through.

Yeah, I was going to say, I think it's more to do with the substation than the roboport.
Place a 2x2 grid of roboports and you'll be able to walk between them both vertically and horizontally.

I've also been surprised by how much the roboport blocks on its north side. I was expecting to be able to build one full tile south of where I actually can. I think if the graphic were changed so it looks like it takes up all space it actually does, either (a) it would have to be changed to a flatter structure or (b) it would obscure things to the north of it. Like the magical length-changing train cars, it's an artifact of the graphical projection they've chosen.