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I have two Wi-Fi modules (Moxa AWK 3131) from MOXA. I am trying to set up these two modules in such a way that they can talk to each other. I have connected them as follows,

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I have configured the MOXA1 as AP and MOXA2 as a client and the IP address of to laptop are chosen under the same sub net that is 192.168.127.xxx

I am able to connect these two MOXA modules and I am also able to ping the IP address of Laptop_A from laptop_B (from Client to AP) but what I am not being able to do is ping the IP address of Laptop_B from Laptop_A (from AP to Client).

Why am I not being able to ping from AP to client? Is AP only listening from client ? Is this set up wrong to make a two way communication? If so, what changes do I need to make in order to establish a two way communication between these two MOXA modules?

  • Could you have a firewall on laptop B? – Ron Trunk Dec 3 '14 at 14:40
  • No it doesn't have firewall enabled. When I switch the laptop I can still ping from Client to AP, so i don't think its because of the firewall. – Electronic Curious Dec 3 '14 at 14:51
  • Does the ap have a firewall? – Ron Trunk Dec 3 '14 at 15:37
  • This is the exact testing scenario proposed in the documentation for this device (down to the exact IPs in use). If it isn't working properly, I would suggest you make sure you are running the most current firmware and then contact their support if it still does not work. I don't see how we could provide a better answer. – YLearn Dec 3 '14 at 15:41
  • Thanks your your reply, what I want to know now is when I make a setup like above can I have a two way communication between AP and client? I wasn't sure if the set up was correct or if the mode selection was going to work. What about changing the mode to Master and Slave? – Electronic Curious Dec 3 '14 at 15:59
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Copying here hat I put in Super User a few days ago:

I had a peek at the not-too-informative manuals and the not-much-more-informative website. I did notice your setup is the same test setup you find in the installation guide. There's the same test, ping from laptop connecting to the Client to the laptop connecting to the AP. If it works, test is successful; there's no mention that pinging the other way should be successful or even tested.

There's four modes; AP, Client, Master and Slave. AP is clear, Master/Slave combo is for creating a wireless bridge (WDS). I guess the Client mode is intended for using this device as a dumb wireless NIC.

In that mode you'd connect the box to Ethernet NIC of another device which has no WiFi capability. The Client is the one which connects to the wireless network, just as a wless NIC does, and acts the same way - passes traffic between the wireless interface and the "bus", i.e. the Ethernet interface. Since the other device is not actually connecting to the network itself, it won't be seen and it shouldn't need an IP address at all.

Run a Wireshark trace on laptop A when you're pinging from laptop B. I bet the ICMP echo packets are originating from IP address .127.254. If I'm right, from the network point of view address .127.1 doesn't exist at all.

I think that if you want specifically laptop B itself to be pingable, you'd need to configure Master/Slave mode. However there's a catch: now .127.253 is in AP mode, which means any wless client can connect to it.

The specs specify two antennas, but I couldn't find out how many radios the device has. One radio can only perform one function, it's either serving the WDS bridge, or serving wireless clients. So if there's only one radio, the Master and Slave can only talk to each other, not to wless clients.

Please do let me know :-)

  • Hello Arimo, thanks for the suggestion. I have the connection running now. I adding two components which are the Serial to Ethernet converter. I connected these converters between the Laptop and the Wi-Fi module on both the side so that I could communicate between two Laptops using serial terminal program. Once the converters were added in my test I was able to prove the Wi-Fi connection was working two way. But I still don't understand why i couldn't ping from AP to client. – Electronic Curious Dec 22 '14 at 13:50
  • Hi curious :) Usually on the network point of view "Client" refers to your device's wireless NIC. Most manufacturers offer wireless Client Bridges which you can connect to for example a printer that only has Ethernet connectivity. I believe that when you configure the AP to be a client, it will act as a Client Bridge (i.e. a dumb wireless NIC), in which case it's the only IP actually showing up in the network. If you run the wireshark trace as I suggested you can check this - if the ping source is the "Client AP" IP, it's a Client Bridge and the behavior is expected. – Peregrino69 Dec 22 '14 at 15:56
  • If so, configuring the Master / Slave should be appropriate. Then your wireless NIC will be the client, show up in the network and be pingable. Since I am not familiar with these devices I would be very curious if my diagnosis is correct :) – Peregrino69 Dec 22 '14 at 15:57

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