Flutter-webrtc for calling not working in public network with my own coturn configured server on my ubuntu computer having public IP

Question

My flutter-webrtc app is working in local network but in public network it is not working even i configured coturn server on my computer which I choose a computer with public IP to be stun/turn server. I think problem is on my coturn server configuration, that I have it in my own server room, and there is no DNS just I have used from public IP of the my ubuntu computer.

thanks in advance

Here is the coturn server configuration that I have tried:

listening-port=3478
listening-ip=181.90.89.54
min-port=49152
max-port=65535
Verbose
lt-cred-mech
user=jankhan:Khan_122122
realm=181.90.89.54
syslog

And here is the flutter code which is working in local and not working in public:

  void _setupPeerConnection() async {
    var configuration = {
      'iceServers': [
        {
          'urls': 'stun:181.90.89.54:3478',
        },
        {
          'urls': 'turn:181.90.89.54:3478',
          'username': 'jankhan',
          'credential': 'Khan_122122',
        },
      ]
    };

    try {
      _rtcPeerConnection = await createPeerConnection(configuration);
      _rtcPeerConnection!.onIceCandidate = (candidate) {
        print('ICE Candidate: $candidate');
      };
      _rtcPeerConnection!.onIceConnectionState = (state) {
        print('ICE Connection State: $state');
      };
      _rtcPeerConnection!.onAddStream = (stream) {
        print('Stream added: $stream');
      };
    } catch (e) {
      print('Failed to create peer connection: $e');
    }

    _rtcPeerConnection!.onTrack = (event) {
      print("Track event: ${event.track.kind}");
      if (event.streams.isNotEmpty) {
        print("Stream received: ${event.streams.first.id}");
        setState(() {
          _remoteRTCVideoRenderer.srcObject = event.streams.first;
        });
      }
    };

    _localStream = await navigator.mediaDevices.getUserMedia({
      'audio': isAudioOn,
      'video': isVideoOn
          ? {'facingMode': isFrontCameraSelected ? 'user' : 'environment'}
          : false,
    });

    _localStream!.getTracks().forEach((track) {
      _rtcPeerConnection!.addTrack(track, _localStream!);
    });

    _localRTCVideoRenderer.srcObject = _localStream;
    setState(() {});

    // Enable speakerphone
    if (_localStream?.getAudioTracks().isNotEmpty ?? false)
      _localStream?.getAudioTracks().first.enableSpeakerphone(true);

    if (widget.offer != null) {
      socket.on("IceCandidate", (data) {
        String candidate = data["iceCandidate"]["candidate"];
        String sdpMid = data["iceCandidate"]["id"];
        int sdpMLineIndex = data["iceCandidate"]["label"];
        _rtcPeerConnection!.addCandidate(RTCIceCandidate(
          candidate,
          sdpMid,
          sdpMLineIndex,
        ));
      });

      await _rtcPeerConnection!.setRemoteDescription(
        RTCSessionDescription(widget.offer["sdp"], widget.offer["type"]),
      );

      RTCSessionDescription answer = await _rtcPeerConnection!.createAnswer();
      await _rtcPeerConnection!.setLocalDescription(answer);
      socket.emit("answerCall", {
        "callerId": widget.callerId,
        "sdpAnswer": answer.toMap(),
      });
      setState(() {
        _isCallAnswered = true;
      });
    } else {
      _rtcPeerConnection!.onIceCandidate = (RTCIceCandidate candidate) {
        rtcIceCandidates.add(candidate);
        print("New ICE candidate: ${candidate.candidate}");
      };

      socket.on("callAnswered", (data) async {
        await _rtcPeerConnection!.setRemoteDescription(
          RTCSessionDescription(
            data["sdpAnswer"]["sdp"],
            data["sdpAnswer"]["type"],
          ),
        );

        for (RTCIceCandidate candidate in rtcIceCandidates) {
          socket.emit("IceCandidate", {
            "calleeId": widget.calleeId,
            "iceCandidate": {
              "id": candidate.sdpMid,
              "label": candidate.sdpMLineIndex,
              "candidate": candidate.candidate
            }
          });
        }
      });

      RTCSessionDescription offer = await _rtcPeerConnection!.createOffer();
      await _rtcPeerConnection!.setLocalDescription(offer);
      socket.emit('makeCall', {
        "calleeId": widget.calleeId,
        "sdpOffer": offer.toMap(),
        'isAudioCall': false,
      });
    }
  }