So I just got this game, so forgive me if this is obvious.

Basically, in certain games I'd have 4 planets in a row, linked by phase lanes only between adjacent planets, like

P1 - P2 - P3 - P4

However, somehow enemies sometimes mysteriously appear at P3, without ever being seen in any of my other planets' vicinities. Note that I'm playing against normal AI, usually 5 player FFA, and this happens around 30min into the game...

Is it generally true that people might have direct phase lanes to your planets without you being able to see the phase lanes? Or is this some special research thing that people have to get?

Apparently you're meant to defend your empire using "phase lane bottlenecks", but I don't see how these bottlenecks can work if they can just appear in the middle of your empire.

thanks