Need help improving defense on this Guardian

https://pobb.in/TtJrWZnz08um

I'm curious, what would it take to to get this build to wave 30 comfortably?

So far, I've made it to wave 15 in the Simulacrum before I get 3-shot into oblivion, and I'm only really having trouble doing T14-T16 rare red maps outside of that. Inside the sim, I can't tell what's killing me but it feels like I'm getting stunned.

Any advice?