IPv6 incoming blocked

Hello,

My Linode has several IPv4 and a IPv6 range.

When I use

ping6 google.com or any other domain inside my linode that has IPv6 the ping works.

When I want to ping a domain, configured with a IPv6, on another instance, other provider and want to ping6 a domain in my own linode it won`t respond.

I disabled all firewalls when testing.
The network manager is disabled, it won't overwrite my config when rebooting.

The distro used Cloudlinux 8 together with WHM\cpanel

The content of my ifcfg-eth0 is the following:

[root@mta42]# cat ifcfg-eth0
# IPv4 Addresses
# Private IPv4 Address
DEVICE="eth0"
NAME="eth0"
ONBOOT="yes"
BOOTPROTO="static"
NM_CONTROLLED="no"

TYPE=Ethernet
# IP: 23.239.XXX.XXX
IPADDR=23.239.XXX.XX
#NETMASK=255.255.128.0
PREFIX0="24"

# IP: 23.239.XXX.XXX
IPADDR1=23.239.XXX.XXX
# GATEWAY1=23.239.XXX.1
# NETMASK1=255.255.255.0
PREFIX1="24"
# Reverse DNS: mail.domain1.com

# IP: 45.33.XXX.XXX
IPADDR2=45.33.XXX.XXX
# GATEWAY2=45.33.XXX.1
# NETMASK2=255.255.255.0
PREFIX2="24"
# Reverse DNS: hello.domain2.com

# IP: 45.79.XXX.XXX
IPADDR3=45.79.XXX.XXX
# GATEWAY3=45.79.XXX.1
# NETMASK3=255.255.255.0
PREFIX3="24"
# Reverse DNS: hello.domain3.com

# IPv6 Addresses
# Link Local IPv6 Address
IPV6INIT=yes
IPV6_AUTOCONF=yes
IPADDR_IPV6=fe80::f03c:XXXX:XXXX:XXXX
NETMASK_IPV6=ffff:ffff:ffff:ffff::
GATEWAY_IPV6=fe80::1

# Range IPv6 Address
# Assign your IPv6 range here

# SLAAC IPv6 Address
IPV6INIT_IPV6=yes
IPV6_AUTOCONF_IPV6=yes
IPADDR_IPV6_IPV6=2600:3c03:XXXX:XXX::/64
NETMASK_IPV6_IPV6=ffff:ffff:ffff:ffff::
GATEWAY_IPV6_IPV6=fe80::1

# IPV6INIT="yes"
IPV6_ADDR_GEN_MODE="eui64"
IPV6_PRIVACY="no"
# IPV6ADDR="2600:3c03:XXXX:XXX::/64"
## IPV6_DEFAULTGW="2600:3c03:XXXX:XXX::1"
## IPV6ADDR="2600:3c03::f03c:XXXX:XXXX:XXXX"
## IPV6_DEFAULTGW="fe80::1"
## IPV6ADDR="2600:3c03::f03c:XXXX:XXXX:XXXX"
## IPV6_DEFAULTGW="fe80::1"


# IPV6ADDR_SECONDARIES="2600:3c03:XXXX:XXXZZ::/64"


# PEERDNS="yes"
# DOMAIN="members.linode.com"
# NETWORKING="yes"
# IPADDR="23.239.XXX.XXX"
#PREFIX="24"
#GATEWAY="23.239.XXX.1"
DNS1="66.228.42.5"
DNS2="97.107.133.4"
DNS3="66.175.211.5"

# Additional IPv4 addresses for eth0
# IPADDR0="45.79.XXX.XXX"
# PREFIX0="24"

# IPADDR1="45.33.XXX.XXX"
# PREFIX1="24"

# IPADDR2="23.239.XXX.XXX"
# PREFIX2="24"

#IPADDR3="192.168.XXX.XXX"
#PREFIX3="17"

My main question is how to get any IPv6 that is inside of my Linode to respond to a request outside of my Linode.

I have a support ticket open to have my EXIM to send out emails on a IPv6 address, the first step to fix this is to get this part to work.

Best,

Mike