So i decided to play through the game with the minuteman ending, however I've run into a problem. I completed the mission to retake the castle, and then infiltrated the institute through the minuteman. Inside the institute i got the holotape information, completed institutionalized, and then banished from the institute. When I returned to sanctuary, I gave the holotape to Sturges. All of this went as I expected it to however, when I talk to Preston he says we need to recruit more settlements before attacking. I already have 12 settlements, and when I follow the missions he gives me it simply takes me to settlements I have already recruited and upon completing those missions, the storyline does not advance. I can not get Preston to trigger "defend the castle". Does anyone have any ideas? Thanks in advance.

check your quest log. i did the MM ending. if i recall correctly, i had to meet father once again to get officially ban.

how far have you gone with the other factions? at some point you will have been boxed in with a faction.

You sure he isnt telling you to build artillery at more settlements? From what I remember you have to build four at four different settlements to attact the prydwin to trigger the attack on the castle

The order of events can be hard to track. I seem to remember getting banished from the Institute then taking my sweet time getting around to having Sturges look for another way inside (you DO have to go back to the Institute after being banished --- just to the locked relay room --- so Father can basically tell you off). I was picking up settlements here and there, and eventually finished Form the Ranks and then I got attacked at the Castle and ~then~ I had Sturges look for another way in.

With the order of events that way, attacking the Institute seems more like ~retaliation~ for them attacking the Castle FIRST, which suits me better than the idea that Preston would go all bloodthirsty slavering maniac and have me nuke civilians ~just because~. Before that attack on the Castle, the only fallout (ha!) from betraying the Institute was some harsh words from Father.

Your Form The Ranks mission sounds like it's not advancing properly. Not sure how many settlements I had at the time... I think maybe all but three or four? So quite a few.

EDIT: Oh, and FWIW, if you are only aggro with the Institute, you do not need to place more Artillery anywhere. I just had the one tutorial-type Artillery station set up at the Castle when the Institute attacked me. By the by, I am ~reasonably~ sure that the game automatically put the Artillery smoke grenades in my grenade slot without asking me --- I thought I was throwing frag grenades but then I noticed I was getting a message that I could not target artillery on friendly forces and when I went into inventory I was able to switch ~to~ Frag grenades.