wss:// not worked (

[xfishernet]

const httpsOptions = {
    key: fs.readFileSync('keys/server.key'),
    cert: fs.readFileSync('keys/server.crt'),
};

const app = websockify(new Koa(), { port: WS_PORT }, httpsOptions);

and if i connect to WS_PORT from WebSocket client via ws://localhost:WS_PORT that's ok, but if I connect via wss://localhost:WS_PORT i get this error:

Connect Error: Error: write EPROTO 4528641472:error:1408F10B:SSL routines:ssl3_get_record:wrong version number:../deps/openssl/openssl/ssl/record/ssl3_record.c:252:

what could it be?