DS is 16, and we are struggling. He has become more and more passive, disconnected and self sabotaging in many areas of his life, hes lost confidence in himself, he is lonely and not happy with his daily life, has no real friends or contacts outside the family but will not do anything about it and (consciously or unconsciously, we aren't sure) sabotages any of our attempts to help by disengaging from any situation that he is not in control of or that might provoke any discomfort or stress. He wants to be good at things and have exactly the daily life he wants without putting in any effort at all and gets very angry/frustrated when he is not instantly capable at or best at anything.
He will not ask for help when he struggles or tell us anything unless it somehow reaches a crisis point where he will be tearful, angry/throw things and eventually tell us what has been going on. He will not ask teachers or others for help and isn't in contact with any sort of peer group. We have probably been a bit lenient and soft with him, in that hes been having a hard time and we thought a online contact/friendships and gaming would be useful/safe for him but he seems to have shut down most other interests and activities and would if given a choice spend all his time online. Hes not on social media and I cant see anything particulary dodgy in his online use but its all really passive predigested review videos commenting on games, films and programs. He keeps to a routine, goes to his classes but sits quietly and does the bare minimum work, isolates at breaktime, never joins groups for projects, eats, sleeps, good with extended family, goes to a single sport with DH, is mostly pleasant as long as you don't demand anything more from him but will not make any sustained effort with anything and has no plans or ambitions, and his response to pretty much any new suggestion is an automatic No.
I would really appreciate any advice from other parents of teens how to help him out of this self defeating isolating phase and help him build some confidence and resilience again