RT-AX86U "Spoof LAN TTL value" option is causing internet break on mobiles

[Alexey8484]

Hey guys,

Recently bought RT-AX86U to replace my old RT-AC87U.
I have updated firmware on AX86U to the latest Merlin release 386.2 and moved all configs manually (without using save-restore setting feature) since RT-AC87U is running on Merlin 384.13_10, so 80% of settings are the same.

Once setup was done I faced the following issue: though Internet works fine on wired PC (on Windows) and Notebook (on Windows) connected via Wifi2.4, Internet doesn't work on all my Wifi connected mobile devices (on Android 11/10/8) and Samsung smartTV (on WebOS).
But if I enable AP to share WiFi on mobile (where Internet doesn't work) and connect another mobile to it, then Internet works fine there!

Simple schematic of connections:

[Internet] <--(wired)-- [AX86U] <--(wifi)-- [mobile1, Internet doesnt work] <--(WiFi over AndroidAP)-- [mobile2, internet works]

After digging settings during 10 hrs I found out that this behavior is caused by enabled "Spoof LAN TTL value" option on WAN page: if I'm disabling that option and reconnecting mobile, then Internet works fine.
That's very strange, because "Spoof LAN TTL value" option was set very long time on AC87U and working fine there.

Any idea why and how "Spoof LAN TTL value" option is causing this issue?

 

[Alexey8484]

Sure: nothing strange in the logs.