How do you turn off IPV6 in FreePBX 17? It seems to be turned on by default.
Is this something configured at your host level ?
How are you running Debian 12 - cloud or metal ?
What parts of FreePBX that are using IPv6 are you concerned with ?
The server is installed on a Vultr Cloud Compute Server. The Server runs fine for about 20 hours and then I get:
Firewall Rules corrupted! Restarting in 5 seconds.
Firewall service now starting.
I tried turning off IPV6 in the OS but the error still occurs.
I noticed that when the firewall is restarting the IPV4 address is missing and only the IPV6 address shows after logging in on the console, so I assume that IPV6 is at fault.
After a reboot, everything works fine for another 20 or so hours.
Is that a static or ephemeral IPv4 ?
Static IPv4 address
Is your server relying on DHCP or is the address static’d in /etc/network/interfaces file or a file in /etc/network/interfaces.d/ directory ?
/etc/network/interfaces file
#This file describes the network interfaces available on your system
#and how to activate them. For more information, see interfaces(5).
source /etc/network/interfaces.d/*
#The loopback network interface
auto lo
iface lo inet loopback
#The primary network interface
allow-hotplug enp1s0
iface enp1s0 inet static
address 45.76.75.197
netmask 255.255.254.0
gateway 45.76.74.1
/etc/network/interfaces.d/enp1s0 file
#Generated network configuration.
#This file was generated at 2025-11-04T22:08:56+00:00
auto enp1s0
allow-hotplug enp1s0
iface enp1s0 inet static
address 45.76.75.197
netmask 255.255.254.0
gateway 45.76.74.1
/etc/network/interfaces.d/50-cloud-init file
#This file is generated from information provided by the datasource. Changes
#to it will not persist across an instance reboot. To disable cloud-init’s
#network configuration capabilities, write a file
#/etc/cloud/cloud.cfg.d/99-disable-network-config.cfg with the following:
#network: {config: disabled}
auto lo
iface lo inet loopback
auto enp1s0
iface enp1s0 inet dhcp
dns-nameservers 108.61.10.10
/etc/network/interfaces.d/ directory only has those 2 files.
So there’s a couple of these lines:
And one of these:
Not sure how well they will play together… 
The /etc/network/interfaces.d/50-cloud-init file is created by the server/OS it can’t be edited or deleted as it is just restored to what is shown on server reboot. I did however, following the directions of that file, create a /etc/cloud/cloud.cfg.d/99-disable-network-config.cfg file with the value of network: {config: disabled}, so the 50-cloud-init file should be ignored.
After more reading it seems that IPV6 shouldn’t be disabled. I have had so much problem with IPV6 in other systems I would rather not deal with it here too. But I still do not know why the firewall crashes and get corrupted daily. I will post more information from the next time it crashes.
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