Nope it's not like that actually. It's spawning Rebel ships that attack anything in sight. Hmm, if my opponents have found an relic, can it cause things like that?. On most of the planets the allegiance is stuck at 60% (with no gains or loss), some are as low as 25%. Strange things. Oh i hope it's not the culture cannon though. There's two advent factions still around.

Actually thats the least of my problems. The AI has allied against me . I think i'm done unless something happens that can make them fight each other again. Maybe even 6vs1 (or heck 8).

The ultimate TEC tech causes Rebel ships to pop up and randomly attack enemy empires. That's pretty much it.

Think of the Rebels as a mixed blessing. Sure, they're causing a mess in your system, but it's better than getting nailed with a novalith cannon. Rebels will attack everyone, even the masters of the culture that spawned them to begin with, so when the enemy shows up to take your rebel-infested system from you it's a 3-way battle. Left to their own targeting priorities, I've observed the rebel and invader fleets trying to take down each other's siege frigates rather than fighting their common enemy!

The point I was trying to make is that, for the TEC player, rebels can actually make it more difficult to take a system, since the rebels will drop what they're doing and attack any siege frigates in the system thanks to the goofy targeting priorities, and the TEC ships, if left alone, will also attack rebel siege frigates who are bombarding the planet the TEC wants to take. The player who actually owns the planet can just sit back with his fleet and wait for the rebels or TEC to win before he really needs to do anything. It's bizzare.

Actually, I've had rebels (multiple heavy cruisers and a dozen or so frigates) damage my force of a Marza (level 4) 2 siege frigs, half a dozen Cobalts, and half a dozen Javelis LRMS enough that I had to retreat. It helped that the rebels were attacking me instead of the Dunov (level 1) belonging to the person they were rebelling against! I know a serious attack force would have wiped both the rebels and the Dunov, but I didn't have one that wasn't busy at the time. Besides, why should I need a full-scale attack force to take down a planet that's had half of its orbital structures destroyed by rebels who theoretically support my cause and is currently being bombarded by those same rebels? If it had been just the enemy defense force, it would have been an overwhelming victory for me, but because 'my' rebels were there I was forced to retreat and come back later. As such a high-level tech, Insurrection should be more useful and less of an annoyance to the player using it. The rebels aren't enough to take a planet on their own, or to even threaten a planet with some decent defenses. They might be useful if they would fight alongside you, allowing you to do more with a smaller attack force, but for now they're only good for harrasing poorly defended planets that you don't have the spare forces to attack yourself, and then only if your opponent allows your culture to reach those planets unopposed!

try using frigs, lrm frigs and support cruisers to fight the rebels. don't divert your main fleets.
Its your turf, so repair bays will heal you constantly while fighters will maul your enemy alongside your little defense group.

Not realy, when going against an *equal* empire all that it does is add an extra sting to the usual culture wars.

How can i manage the allegiance on big maps (10+ stars, 100-200 planets).

My planets always stuck at 25-35 %. i build broadcast centers on each planet but i couldnt get them to 50+% .

35% is basically the "standard" allegiance level for outlying planets which are like 6+ hops away from your capital. There is nothing you can really do about it. The standard allegiance will be 25%, +10% for friendly culture, +10% for maxing the Advent allegiance tech. That's all you can do, short of moving your home planet to a more central location, which will just shift the issue around. More broadcast centers will not really help, it doesn't sound like you actually have culture problems. And yeah, a cannon and hangar cluster supported by some repair bays will shred pretty much all rebel assaults with no real intervention from you.