There's a decision where you can infiltrate the vault, did you do that? Also you need to repeat infiltration many times to get all phanon techs, you get random tech(s) after winning the fight.

you mean the decision pop up on the phanon vault window like planets decision ? if yes it did not appear

I made a new game and this this time I got an event asking me to disable the phanon mirror, and the vault decision was there too, I guess the event didn't trigger in my previous game.