Is is range from a friendly planet, or starbase?
Yes that is it exactly.
What would cause the range to decrease in the game if I have the same planets and starbases and all of a sudden battleships that were in range are now out of range?
My best guess would be that you upgraded your ships? The auto-generated ships use life support as a filler and will sacrifice it if they can fit more weapons. The only other possibility I can think of is that you lost a planet or starbase without realizing it.
