In order to set a custom TTL value for forwarded packets from the internal network, follow these steps:


SSH into the router CLI as the root user with the admin password and find the interface name of the WAN interface with the ip command


ip addr show


Test the command below using your WAN interface name and required TTL value, the example below shows interface name wwan0 and setting a TTL of 64


iptables -t mangle -I POSTROUTING -o wwan0 -j TTL --ttl-set 64

If that works for your purposes add it into the rc.local file using the intructions below. If it doesn't work then a reboot will clear it and you can start from fresh and retest.


Assuming you want to keep your new TTL after reboots then add it to the rc.local file. Execute the following command to open rc.local file in a text editor


vi /etc/rc.local

Press "i" button on your keyboard to start editing the file (insert mode).

Insert the line from your tested command e.g. iptables -t mangle -j POSTROUTING -o wwan0 -j TTL --ttl-set X



Press "Esc" button on your keyboard and enter ":w" to save the file, then ":q" to quit

Execute the following command to run the script: sh /etc/rc.local (or reboot)


sh /etc/rc.local




Note: if you want to set a TTL for traffic originating from the router use the --ttl-inc command (instead of --ttl-set)


iptables -t mangle -I POSTROUTING -o wwan0 -j TTL --ttl-inc X