so I heard that synth infiltrators will make attacks in your town.. how to detect them? is there a way?

Well, synths have natural energy resistance, so if you have the Awareness perk in VATS you'll be able to see what's going on.

this s a new patch thing?

I've heard that if you have the Awareness perk, Synths will have extra Energy Resistance than what they get from their equipment, but I can't confirm this.

It`s just rumours about energy resistance. I had a synth with zero energy resistance. There is no way to detect without killing settlers. Detecting them is pointless. Synth attack is a random defend quest. If you will not get a synth attacks, you will get raider attacks or some other kinds of attacks. Makes no difference apart from loot.

Synths will always have higher resistances than their human counterparts AFAIK. However, not everyone takes the Awareness perk. There is the D13 Settlement Institute Spy Detection and Elimination mod on Nexus Mods, but that only applies to PC users. It involves a modified Tesla Arc that stuns any Synth spies and you can use a ring to turn them hostile so you and your Synth-fearing Settlers can destroy them without the other Settlers turning on you. The plans for these items are found in a certain underground facility.

Sorry, but this is a myth. I just went and used VATs on my synth settler and he has 0 energy resistance, and 0 of any other resistance. I have Awareness perk. I know he is a synth though. I had a synth attack in this settlement and he was killed by other settlers and had a synth component . But I loaded a save for other reasons so he is still alive now.

Hmm. It seems to have flawlessly for my son . Maybe only some show up. He hasn't killed any real settlers once he learned to check for energy resistant gear. Never tried it myself. He even detected a Synth Brahmin

That is interesting . Well, I`m sure that synth settlers can have 0 energy resistance. I saw it myself. Maybe some of them are different. I just don`t kill any settlers ever , so I did not bother to check them all. Not their fault that the Institute uses them. I don`t mind synths in my settlements and I don`t mind synth attacks ( nice armor loot+ fusion cells).

But I remember I used VATs on those Art guys ( 2 similar guys fighting in random locations) and one of them really had some energy resistance.

yeah if your happiness drops often its because of a synth, I had 3 brahmins turn synth in 3 different settlements

they also start acting weird, codsworth killed one

Myth . Happiness drops for no reasons because of the number bug (the system is bugged right now and messes up numbers when you not in the location. And it not only shows them wrong in pip boy , it really thinks that they are this way. So when the system thinks that you have lack of resources ( even if you have no lack of them) it makes happiness go down. This bug can also make happiness go up for no reason and it allows you to send a lot of settlers to one settlement , much more than your charisma allows. I don`t recommend to do it though.

Just yesterday I've discovered this video, maybe it is on to something...

https://www.youtube.com/watch?v=1hZ1O_Qzv8M