Rails production, trilogy can't connect to remote db but mysql2 can

Trying to switch our production Rails 7.1.3 server from mysql2 to trilogy to connect to two dbs:

• our remote mysql db at DB_IP_ADDR on a separate DO droplet
• our local solid_cache mysql db on our webserver DO droplet at PRODUCTION_IP_ADDR

Because of the known issue with trilogy not being able to use mysql 8's caching_sha2_password, I've already reverted mysql to use mysql_native_password, on both the remote mysql server and the production (localhost) cache mysql server:

# on DB_IP_ADDR

mysql> ALTER USER 'us'@'PRODUCTION_IP_ADDR' IDENTIFIED WITH mysql_native_password BY 'password';
mysql> FLUSH PRIVILEGES;

# on PRODUCTION_IP_ADDR

mysql> ALTER USER 'us'@'localhost' IDENTIFIED WITH mysql_native_password BY 'cache_password';
mysql> FLUSH PRIVILEGES;

Our config/database.yml

production:
  primary:
    adapter:  trilogy
    database: remote_production_db
    host:     DB_IP_ADDR
    username: us
    password: password
    socket:   /var/run/mysqld/mysqld.sock
    encoding: utf8
  cache:
    adapter:  trilogy
    database: our_solid_cache_db
    host:     127.0.0.1
    username: us
    password: cache_password
    socket:   /var/run/mysqld/mysqld.sock
    endoding: utf8
    migrations_paths: "db/cache/migrate"

The local cache db connects fine with trilogy, but the remote db connection fails with

ActiveRecord::DatabaseConnectionError: There is an issue connecting to your database with your username/password, username: us. (ActiveRecord::DatabaseConnectionError)

Please check your database configuration to ensure the username/password are valid.
...

Caused by:
Trilogy::BaseConnectionError: 1045: Access denied for user 'us'@'localhost' (using password: YES) (Trilogy::BaseConnectionError)

I've double-checked the password and it's right: If i switch the database.yml back to adapter: mysql2 without changing anything else, both db connections are OK.

I notice the error message identifies the attempted user connection as 'us'@'localhost', but the request is not coming from localhost, it's coming from PRODUCTION_IP_ADDR.

Is there something special I need for Trilogy to connect to a remote db, or identify a remote user?