RUTX-R1 Mobile WAN is not working from remote site

we are using RUTX-r1 router for an ATM machine, when using wan connectivity we can communicate from ATM lan to Remote server and vise versa, but the issue is when using 4G mobile sim. When we ping remote server from PC it’s no issue but the reverse is not responding.

The remote server is behind firewall and it’s configured accordingly, the log shows a hit for Tx, but shows zero on Rx.
Can you please assist me on this.


Firstly, would it be possible for you to clarify if you are using a SIM card with public IP address or a private APN? What is the IP address of your mobile (mob1s1a1) interface in Network → Interfaces?

Also, are you trying to ping the device in LAN or the RUTXR1 itself?

Kind Regards,


The SIM card is a private APN(data only)
The mobile(mob1s1a1) Ip address get’s DHCP from specific /24 range. where the service provider gave us.
We have pinged a remote server from the LAN side and it is successful. the problem is we can not ping the LAN from the remote side.


You mentioned that you cannot ping from server to RUTXR1 LAN, but can you ping the mobile interface of RUTXR1?

Kind Regards,

Yes that is correct,

this is only happening for mobile SIM but when using wan port the ping works both ways


You mentioned that the mobile interface receives a private IP with a /24 mask. What is the subnet on the LAN and the subnet on the mobile interface?

Are there any other routers/gateways/firewall in the LAN or RUTXR1?

Could you please check if the router receives pings on the mobile interface when you ping the LAN devices from the server? For this, access the RUT via CLI/SSH with username ‘root’ , install tcpdump and run it on the mobile interface interface:

# install tcpdump
opkg update
opkg install tcpdump
# run tcpdump on mobile interface and look for pings
tcpdump -i wwan0 icmp
# if tcpdump fails on wwan0, try qmimux0
tcpdump -i qmimux0 icmp

While tcpdump runs, try pinging the LAN devices from the server. Are there any pings?

Kind Regards,

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