how to set TTL to 65 on asus merlin router for all clients ?

[bestofcomputer]

how to set TTL to 65 on asus merlin router for all clients including non windows clients ?
I know 2 ways of doing this on linux, but is it possible on asus merlin, and how to make it possible, or why is it not possible, and when will it be included in a next merlin release ?
first method on linux : command :
iptables -t mangle -I POSTROUTING -j TTL --ttl-set 65
second method on linux :
add a line in text file /etc/sysctl.conf :
net.ipv4.ip_default_ttl=65
my goal is to defeat certain ISP who checks TTL to decline unlimited plans to clients connected to the router whereas the unlimited plan is working fine when the sim card is used directly from a mobile.
my plan is to buy the ASUS 4G-AC68U, but only if TTL is customizable by either original ASUSWRT or by Merlin.
thanks.

 

[kfp]

asuswrt(-merlin) IS Linux..

 

[bestofcomputer]

I did not mean the contrary.
but in certain old threads from 2015 and 2016 in some forums I have found some people trying to change TTL on ASUSWRT or on Merlin and it was failing because some packages regarding TTL were not included in ASUSWRT or in Merlin.
so I must ask it again, because I dont want to buy a router that I will not be able to change its TTL : how to change TTL on an asus router either by its original ASUSWRT or by Merlin ?
to be sure, actually, I need to see with my own eyes that the procedure exists and what it looks like to do it.
thanks.

 

[kfp]

Ah, prospective buyer, I was wondering why you haven’t just tested it yourself, you sound like you know what you’re doing [emoji4]

Edit: spellinf

 

[john9527]

my plan is to buy the ASUS 4G-AC68U

4G-AC68U isn't supported by Merlin....only RT-AC68U