Depot A is kind of an idiotic bottleneck, because it tests your understanding of the game very early, when you haven't had enough time to learn and there's no way to avoid going in there. It's a pain in the ass for the first timers, but gets pretty trivial once you know what you are doing.
Well, I followed advise of the guy above. Bought myself a set of steel plates, crafted ten bear traps, bought couple more. As I heavily invest in stealth I can move somewhat freely and prepare battlefield, and thus I laid down all the traps, creating a fucking minefield. Then it is: grenades, special shots, retreating out of the line of sight, worked quite well.
Thing is, what if I don't have stealth? Mutie kills me with two acid sprays, and there's like four of them there. I still haven't meet a single syphoner, so for now I don't even know that they exist. No stealth - restart?
And you don't have to tell me about managing line of sight and bottlenecking - I played Fallout, ok? Though, venerable tactic of doorfighting is significantly less effective in Underrail. Kiting is less effective because of distinct movement points. But turrets are dispatched in exactly the same way.
Although, now I get it: traps are OP in Underrail. This comes as a surprise, especially after so many similar games with absolutely useless traps skill.