[root@s22405-ip6 ~]# cat /etc/hosts
127.0.0.1   localhost localhost.localdomain localhost4 localhost4.localdomain4
::1         localhost localhost.localdomain localhost6 localhost6.localdomain6
fd63:6f75:6368:2060:e491:d2ff:fe35:d390 s22405-ip6.qe.couchbase.com s22405-ip6
172.23.97.192 s22405-ip6.qe.couchbase.com s22405-ip6    ---------------------------------> This is important as it needs to resolve to both IPv4 and IPv6 addresses 
[root@s22405-ip6 ~]# 
[root@s22405-ip6 ~]# cat /opt/couchbase/VERSION.txt 
7.0.2-6512
[root@s22405-ip6 ~]#  /opt/couchbase/bin/couchbase-cli ip-family -c http://localhost:8091 -u Administrator -p password --get
Cluster using ipv6only
[root@s22405-ip6 ~]# lsof -i -P -n  | grep LISTEN |  grep couchbase | grep IPv4
[root@s22405-ip6 ~]# 
[root@s22405-ip6 ~]#  /opt/couchbase/bin/couchbase-cli ip-family -c http://localhost:8091 -u Administrator -p password --set --ipv4only
Switched IP family for node: http://s22405-ip6.qe.couchbase.com:8091
SUCCESS: Switched IP family of the cluster
[root@s22405-ip6 ~]#  /opt/couchbase/bin/couchbase-cli ip-family -c http://localhost:8091 -u Administrator -p password --get
Cluster using ipv4only
[root@s22405-ip6 ~]# lsof -i -P -n  | grep LISTEN |  grep couchbase | grep IPv6
[root@s22405-ip6 ~]#