I think recently the AI just hates and gangs up on me at some point, especially when my fleet is out and about...other AI teams come out of nowhere and raid my planets where my defenses do absolutely nothing, even fully upgraded starbases. How do you setup defenses to deal with AI in general? (I still haven't gone online, mainly because I notice almost everyone is considered a "hardcore player") Before I normally played as the Advent because I loved their planetary defenses the most, but recently the AI is starting to even take that down with ease. I usually went with putting a Starbase near the planet, along with a nearby Hangar or two and surround the Starbase with Beam platforms, keeping the Synergy and Shield Bestowal (however you spell it) in mind...That way my Starbase could use Mass Disorientation to hold the enemies in place while the Beams would take them out. And the Homing Mines I throw in later on just damages them even further.
Like I said, before this used to take invading fleets out in a minute or two...but it seems the AI now knows what they're dealing with and spams a certain ship or whatever it takes to take my defenses out in seconds. :/ (by the time my fleet makes it back to chase them away, everything is pretty much destroyed...and the enemy fleet pretty much escapes)
Yeah...its pretty annoying now, lol.