My Galera Cluster does not connect across AWS regions I am building a MariaDB Galera Cluster, on AWS, EC2. Using MariaDB 10.5 and Galera 4.
I have two nodes in the California region, named galera_ca and galera_ca2, and a third node in Oregon name galera_or
The security groups between the servers are wide open, and the ping time between OR and CA is 12ms
I started galera_ca using galera_new_cluster
I started galera_ca2 using systemctl start mariadb

The two California nodes connect and share data just fine. 
wsrep_cluster_size indicates that I have two nodes in the cluster.

I started galera_or using systemctl start mariadb

Oregon then hangs on starting for a very long time, and wsrep_cluster_size shows three nodes, but the server cannot be connected to.
Eventually systemctl start mariadb returns this message: 
Job for mariadb.service failed because a fatal signal was delivered to the control process. See &quot;systemctl status mariadb.service&quot; and &quot;journalctl -xe&quot; for details.
systemctl status mariadb.service doesn't show anything exceptional,
journalctl -xe shows: 
requested state transfer from 'any', but it is impossible to select State Transfer donor: Resource temporarily unavailable
wsrep_cluster_size still shows three nodes, but mariadb is not running in OR. 
If I try to shut down either of the California servers systemctl stop mariadb it never returns.
All three servers have basically the same configuration:
[galera]
wsrep_on=ON
wsrep_provider=/usr/lib64/galera-4/libgalera_smm.so

wsrep_node_name='galera_ca'
wsrep_node_address=&quot;INTERNAL ADDRESS OF THIS NODE&quot;

wsrep_cluster_name='galera-experiment'
wsrep_cluster_address=&quot;gcomm://EXTERNAL ADDRESS OF NODE CA, EXTERNAL ADDRESS OF NODE CA2, EXTERNAL ADDRESS OF NODE OR&quot;

wsrep_provider_options=&quot;gcache.size=300M; gcache.page_size=300M&quot;
wsrep_slave_threads=4
wsrep_sst_method=rsync

binlog_format=row
default_storage_engine=InnoDB
innodb_autoinc_lock_mode=2
bind-address=0.0.0.0

If I try just one CA node and the OR node, the result is the same.
In wsrep_node_address on Amazon EC2, you must use the global DNS name, instead of the internal IP address.