I sometimes use a GL-iNet AR750S Slate instead of tethering to my phone. It’s a nice, compact device, but I needed to change the TCP/IP TTL for one application. Here’s how:
SSH to the router (per docs):
ssh root@192.168.8.1
The root password is the same as for accessing the web console.
From there you can go ahead and edit the contents of /etc/firewall.user and do a /etc/init.d/firewall restart. (It’s likely a reload would work there, but restart is more certain.)
…But the OpenWRT LuCi web interface is what most people use.
Update the opkg package list and install luCi:
opkg update
opkg install luci
Sign in to LuCi (per docs): http://192.168.8.1/cgi-bin/luci
The username is root. The password is same as the one that you use to access the web Admin Panel
Now go to the firewall custom rules in your browser: http://192.168.8.1/cgi-bin/luci/admin/network/firewall/custom
Add a block like the following:
#start TTL fix
#learn more info at https://maisonbisson.com/post/gli-inet-ttl/
ip6tables -t mangle -I POSTROUTING -j HL --hl-set 65
iptables -t mangle -I POSTROUTING -j TTL --ttl-set 65
#end TTL fix
Now go to the firewall status page and click the button to restart the firewall: http://192.168.8.1/cgi-bin/luci/admin/status/iptables
Now go to a site like Speedtest.net to confirm it’s all still working: https://www.speedtest.net
Additional related docs: