diff --git a/src/ui/lib/database-transfer-url.ts b/src/ui/lib/database-transfer-url.ts
index c7394bd30..db19cac1d 100644
--- a/src/ui/lib/database-transfer-url.ts
+++ b/src/ui/lib/database-transfer-url.ts
@@ -20,7 +20,9 @@ export function getDatabaseTransferUrl(
     return `${serverUrl.replace(/\/$/, "")}/database/${operation}`;
   }
 
-  const development = location.port === "5173";
+  // Vite moves off 5173 when another dev server holds it.
+  const development =
+    process.env.NODE_ENV === "development" || location.port === "5173";
 
   if (development) {
     return `http://localhost:30001/database/${operation}`;
diff --git a/src/ui/lib/plugin-transport.ts b/src/ui/lib/plugin-transport.ts
index 2df0aea2c..501bd4b64 100644
--- a/src/ui/lib/plugin-transport.ts
+++ b/src/ui/lib/plugin-transport.ts
@@ -175,11 +175,10 @@ export async function pluginWsUrl(
   const protocols = websocketAuthProtocols(token);
 
   // Dev without a configured API host goes through Vite's proxy, which is
-  // reached on the page's own origin rather than the backend port.
+  // reached on the page's own origin rather than the backend port. Vite moves
+  // to another port when 5173 is taken, so the port says nothing here.
   const devProxy =
-    process.env.NODE_ENV === "development" &&
-    !import.meta.env.VITE_API_HOST &&
-    (window.location.port === "3000" || window.location.port === "5173");
+    process.env.NODE_ENV === "development" && !import.meta.env.VITE_API_HOST;
 
   const wsProtocol = window.location.protocol === "https:" ? "wss" : "ws";
 
diff --git a/src/ui/tests/lib/plugin-transport.test.ts b/src/ui/tests/lib/plugin-transport.test.ts
index 15f665d3c..86c31281e 100644
--- a/src/ui/tests/lib/plugin-transport.test.ts
+++ b/src/ui/tests/lib/plugin-transport.test.ts
@@ -111,6 +111,21 @@ describe("pluginWsUrl in the browser", () => {
     expect(target?.protocols).toEqual(["termix.jwt.ticket-1"]);
   });
 
+  it("goes through the Vite proxy in dev on any port", async () => {
+    vi.stubEnv("NODE_ENV", "development");
+    try {
+      fetchMock.mockResolvedValueOnce(
+        new Response(JSON.stringify({ ticket: "ticket-1" })),
+      );
+      const target = await pluginWsUrl("ssh-terminal", "/terminal");
+      expect(target?.url).toBe(
+        `ws://${window.location.host}/__termix_api/30001/plugin-ws/ssh-terminal/terminal`,
+      );
+    } finally {
+      vi.unstubAllEnvs();
+    }
+  });
+
   it("falls back to the cookie alone for a guest", async () => {
     fetchMock.mockResolvedValueOnce(new Response("{}", { status: 401 }));