Block other NAT-Routers in LAN

[Tryano95]

Hello,

do you know any possible way to block other (NAT-)Routers in my LAN-Network?

I was thinking about setting the TTL to 1 (LAN direction) on pfSense but it seems like this is not intended. So i am searching for another solution, to detect or block secondary NAT/Routing.

Thanks and regards,
Marius