diff --git a/docs/setup.md b/docs/setup.md
index 64f1b4477..53a6fb28c 100644
--- a/docs/setup.md
+++ b/docs/setup.md
@@ -196,6 +196,34 @@ docker compose exec odysseus nvidia-smi -L
 
 For first-time local model testing on 8 GB laptop GPUs, start with GGUF/Q4 models on llama.cpp before trying GPTQ/AWQ models on vLLM or SGLang. This keeps the first run simpler while confirming GPU passthrough works.
 
+**WSL2 + snap Docker.** If the NVIDIA check fails with this error, Docker may be
+installed via snap:
+
+```text
+failed to fulfil mount request: open /usr/lib/wsl/lib/libdxcore.so: no such file or directory
+```
+
+Check with `snap list docker` or:
+
+```bash
+docker info --format '{{.DockerRootDir}}'
+```
+
+A Docker root under `/var/snap/docker/` means snap confinement can prevent
+Docker from seeing WSL2's `/usr/lib/wsl/lib` GPU libraries even when the files
+exist on the host. Reinstalling or reconfiguring `nvidia-container-toolkit` will
+not fix that. Remove snap Docker, install the official apt-based Docker Engine
+([Docker docs](https://docs.docker.com/engine/install/ubuntu/)), then configure
+the NVIDIA runtime again:
+
+```bash
+sudo snap remove docker
+sudo nvidia-ctk runtime configure --runtime=docker
+sudo systemctl restart docker
+```
+
+Then re-run `scripts/check-docker-gpu.sh`.
+
 Safety notes:
 - The app never installs host GPU runtime automatically.
 - The app never edits `.env` automatically.
diff --git a/scripts/check-docker-gpu.sh b/scripts/check-docker-gpu.sh
index b80122ee2..22e6eb539 100755
--- a/scripts/check-docker-gpu.sh
+++ b/scripts/check-docker-gpu.sh
@@ -214,6 +214,22 @@ _check_nvidia_smi() {
     echo
 }
 
+# WSL2 snap Docker cannot see /usr/lib/wsl/lib/libdxcore.so from its confined
+# namespace, so NVIDIA passthrough fails until the user switches to non-snap
+# Docker. DockerRootDir identifies snap installs more reliably than snap(8).
+_is_wsl() {
+    grep -qi microsoft /proc/version 2>/dev/null && return 0
+    [ -d /usr/lib/wsl ] && return 0
+    return 1
+}
+
+_is_docker_snap() {
+    case "$(docker info --format '{{.DockerRootDir}}' 2>/dev/null)" in
+        */snap/docker/*|*/snap.docker/*) return 0 ;;
+    esac
+    return 1
+}
+
 # Returns 1 if Docker is unavailable (callers should stop further GPU checks).
 _check_docker() {
     _info "Checking Docker..."
@@ -258,6 +274,26 @@ _check_gpu_passthrough() {
         echo
         _fail "GPU passthrough failed. Check these steps in order:"
         echo
+        if _is_wsl && _is_docker_snap; then
+            _warn "Detected: Docker installed via snap, running on WSL2."
+            _warn "This is a known incompatibility, not a toolkit/config problem:"
+            _warn "  snap confines Docker's mount namespace, so it cannot see the"
+            _warn "  WSL2-injected GPU library at /usr/lib/wsl/lib/libdxcore.so even"
+            _warn "  though the file exists on the host. Installing/reconfiguring"
+            _warn "  nvidia-container-toolkit will NOT fix this — the numbered"
+            _warn "  steps below will not help until Docker itself is replaced."
+            echo
+            _info "Fix: remove snap Docker and install the official apt-based Docker"
+            _info "Engine instead (unsandboxed, can see /usr/lib/wsl/lib):"
+            echo
+            echo "  sudo snap remove docker"
+            echo "  # then follow: https://docs.docker.com/engine/install/ubuntu/"
+            echo "  sudo nvidia-ctk runtime configure --runtime=docker"
+            echo "  sudo systemctl restart docker"
+            echo
+            _info "Re-run this script afterward to confirm passthrough works."
+            echo
+        fi
         echo "  1. Install NVIDIA Container Toolkit (if not already installed):"
         echo "     Arch:    sudo pacman -S nvidia-container-toolkit"
         echo "     Debian:  sudo apt install nvidia-container-toolkit"