If both h264 and hevc are stuttering using hardware decoding, something might be wrong. Try setting up Apollo or sunshine on your remote PC, and add Moonlight to your deck using the desktop App Store.
There are lots of guides online for how to install Moonlight and add it to your deck’s games list.
If that works smoothly with hardware decoding, then the problem is with remote play.
I wrote out the rest of this before rereading your post and want to put it out there for others:
If you’re having issues with hevc, switch back to h264.
Hevc is more computationally complex to encode/decode, so if you’re trying to do either with software, then it would be better to use the less compressed h264.
Network congestion over WiFi, as you pointed out, is often also a culprit.
What is your domicile like? An apartment with lots of nearby apartments? Freestanding house? WiFi congestion gets worse with more people using it.
If you have a dock, plug in an Ethernet cable to the dock and try streaming that way. Does it mitigate your stutter?
If so, turn down the bandwidth as much as you can and check (e.g 720p at 30 fps).
If it is that, buying a higher quality wifi access point may help.
Also, he spelled Semitic wrong both times!