Simple Network-Geometry Node Practice

I created this asset by following a tutorial made by Ducky 3D: https://www.youtube.com/watch?v=vcESjx01DdA.

Ducky 3D's channel link: https://www.youtube.com/@TheDucky3D

For some reason, parts of the network have curved bends when they are only connected to two points instead of being straight lines. It would be appreciated if anyone could tell me how to connect this issue.