diff --git a/core/archipelago/src/api/rpc/middleware.rs b/core/archipelago/src/api/rpc/middleware.rs
index 7489f51b..ac029f36 100644
--- a/core/archipelago/src/api/rpc/middleware.rs
+++ b/core/archipelago/src/api/rpc/middleware.rs
@@ -66,6 +66,9 @@ pub(super) fn sanitize_error_message(msg: &str) -> String {
         "Bitcoin address",
         "No router",
         "No OpenWrt",
+        "No space left",
+        "TollGate installation failed",
+        "No pre-built TollGate",
     ];
     for prefix in &user_facing_prefixes {
         if msg.starts_with(prefix) {
diff --git a/core/openwrt/src/tollgate/install.rs b/core/openwrt/src/tollgate/install.rs
index 4b1beb81..64b9a5e6 100644
--- a/core/openwrt/src/tollgate/install.rs
+++ b/core/openwrt/src/tollgate/install.rs
@@ -48,8 +48,27 @@ pub fn install_tollgate(router: &Router) -> Result<()> {
 
     info!("[{}] Downloading TollGate for {} from GitHub releases", router.host, arch);
     router.run_ok(&format!("wget -O /tmp/tollgate.ipk '{}'", url))?;
-    router.run_ok("opkg install --force-depends /tmp/tollgate.ipk")?;
+
+    // Capture stderr too — BusyBox opkg exits 0 even on "Cannot install" failures.
+    let (out, _code) = router.run("opkg install --force-depends /tmp/tollgate.ipk 2>&1")?;
     router.run_ok("rm -f /tmp/tollgate.ipk")?;
 
+    if out.contains("Cannot install") || out.contains("errors encountered") {
+        if out.contains("Only have") && out.contains("available on filesystem") {
+            // Extract the sizes from the error for a user-readable message.
+            // Example: "Only have 8884kb available on filesystem /overlay, pkg tollgate-wrt needs 18750"
+            anyhow::bail!(
+                "No space left on router for TollGate ({}). \
+                 This router has insufficient flash storage. \
+                 Consider a router with ≥32 MB flash or add an extroot USB drive.",
+                out.lines()
+                    .find(|l| l.contains("Only have"))
+                    .unwrap_or("check router disk space")
+                    .trim()
+            );
+        }
+        anyhow::bail!("TollGate installation failed: {}", out.trim());
+    }
+
     Ok(())
 }