cppzmq fails to receive tcp messages

Question

I am trying to use ZMQ socket on my Ubuntu machine to communicate with a ESP8266 edge device. I tried this piece of Python code which works fine:

import zmq

ctx = zmq.Context()

router = ctx.socket(zmq.ROUTER)
router.router_raw = True

router.bind("tcp://*:8081")

while True:
    msg = router.recv_multipart()
    identity, body = msg

    print(identity)
    print(body)

as it gives (server side)

b'\x00k\x8bEg'
b''
b'\x00k\x8bEg'
b'hello from ESP8266'
b'\x00k\x8bEg'
b'\r\n'

but when I translate it into C++ as

#include <zmq_addon.hpp>

int main () {
    zmq::context_t context;
    zmq::socket_t socket(context, zmq::socket_type::router);
    int router_raw = 1;
    zmq_setsockopt(&socket, ZMQ_ROUTER_RAW, &router_raw, 1);
    socket.bind("tcp://*:8081");

    while (true) {
        std::cout << "listening " << std::endl;
        std::vector<zmq::message_t> msgs;

         if (zmq::recv_multipart(socket, std::back_inserter(msgs))) {
            std::cout << "got " << static_cast<const char *> (msgs.front().data())
                << std::endl;
         }
    }
    return 0;
}

it doesn't work any more and hangs before recv_multipart, though at the same time ESP8266 client do recieve some wierd ⸮ symbol which indicates tcp connection success I guess.