Maybe I’m a one dimensional fly fisherman (need tips)

(Tldr at the end) I've fly fished for a long time, over a decades. Read lots. Talked with a lot of fly fisherman. Got fish almost wherever I fish, rather for trout or smallies.
But this past weekend I quickly realized I was not good at fly fishing.
Went up to northern Michigan to fish for wild trout on one of the best rivers in the state. Tried drifting a terrestrial with a dropper nymph like I often will to feel out the water. It usually works for me. After almost four hours of a really good looking river, drifting my flies through the current I had caught exactly one 8 inch rainbow.
Next day. Four hours of fishing upstream one or two bites. Nothing.

But then a kayaker passes by me. He said he has caught 24 trout that morning in a few hours, 8 of them over 12 inches. So I'm dismayed. I talked to him for a while and he says he's been fishing for 30 years there and he uses almost exclusively mepps, always targeting the undercut banks.

So I tried that with a clouser minnow and wooly bugger for hours. Nothing.

Switched to a spinner, and then started getting bites and chases.

TLDR:So here's my thing. I can do the fly fishing where I drift flies through current. But when it comes to pulling out browns of deep cover, through a fly with action (presumably a streamer) I've got no technique, I've got hardly any knowledge and I was unable to read the water before being told where they are.

How, in a small right stream do you get fish out o cover and present a fly that they will hit (I don't think they cared for my streamers) and why are they there in the first place. Is it because they are wild fish and more wary? Because they are more pressured? Because the river is shallow (2-5 feet)? Because of the season (September), because of the food availability?

I'm looking for answers, I feel beaten.