[root@prometheus ~]# sysctl -a | grep disable_ipv6
sysctl: reading key "net.ipv6.conf.all.stable_secret"
net.ipv6.conf.all.disable_ipv6 = 0
sysctl: reading key "net.ipv6.conf.br0.stable_secret"
net.ipv6.conf.br0.disable_ipv6 = 0
sysctl: reading key "net.ipv6.conf.default.stable_secret"
net.ipv6.conf.default.disable_ipv6 = 0
sysctl: reading key "net.ipv6.conf.ens19.stable_secret"
net.ipv6.conf.ens19.disable_ipv6 = 0
sysctl: reading key "net.ipv6.conf.eth0.stable_secret"
net.ipv6.conf.eth0.disable_ipv6 = 0
sysctl: reading key "net.ipv6.conf.lo.stable_secret"
net.ipv6.conf.lo.disable_ipv6 = 0
sysctl: reading key "net.ipv6.conf.tap0.stable_secret"
net.ipv6.conf.tap0.disable_ipv6 = 0
sysctl: reading key "net.ipv6.conf.vb-nsdc.stable_secret"
net.ipv6.conf.vb-nsdc.disable_ipv6 = 0
you have ipV6 disabled on your server…that not good
from dnutan