RMU500EK is blocking incoming traffic

IoT Modules 5G Module
1

We are using two RMU500EK in our lab but suffer from connectivity issues for a while now: The modem seem to block incoming traffic. Both RMU500EK are connected to a private 5G SA network. Besides, we are using other 5G equipment as 5G routers and Smartphones from different vendors. The 5G core is fully controlled by ourselves so we are aware of all IP addresses assigned by the 5G core to the 5G devises.

The modem is connected over USB to a Windows or Linux Machine. From here we can reach all nodes in the network, that means, ping test is working. However, incoming traffic seems to be blocked by the modem: Every ping request from outside (from 5G core or other 5G nodes) fails. Therefore, we cannot, for example, access a video streaming server (that is running on a PC, connected to 5G over the RMU500EK).

On the modems, we are using the latest firmware (RM500QGLABR13A03M4G). Since other 5G nodes (e.g. smartphones) do respond on ping request (using the IP assigned by the 5G core), this is not a routing issue in our 5G backend. Moreover, there is no firewall active on the PC (Linux or Windows). How can we access the PC, connected via RMU500EK, from external devices? We already tried the passthrough mode without success. Is there anything we must set or configure in the modem to allow incoming traffic?

2

Dear @karl
You mean you can’t ping IP address of module from other device, right?
Are you check the IP address on module side?

3

Yes, that’s true. Ping does neither work from other devices nor from the core itself. For ping we use the IP assigned by the core. It is the same IP, that is visible at the client computer connected to the modem.

4

Dear @karl
Please try to capture wireshark log and see why the ping operator was failes.

5

Thank you for this note. We performed a wireshark log at the UE and Core side. Here we could find out that indeed the Windows Machine itself is blocking incoming ping requests. This seems to be the default setting for modems. We changed the related firewall rule and could now successfully ping the UE from core site. We will next clarify what caused the ping blockage at the Linux based UE.