I use latest mongoid and moped code from repo.

• Start application under puma 3 workers each with 8 threads and use
  Unable to find source-code formatter for language: pool_size. Available languages are: actionscript, ada, applescript, bash, c, c#, c++, cpp, css, erlang, go, groovy, haskell, html, java, javascript, js, json, lua, none, nyan, objc, perl, php, python, r, rainbow, ruby, scala, sh, sql, swift, visualbasic, xml, yaml

  : 25

  for mongoid. Check that all works.

• Stop service
  Unable to find source-code formatter for language: mongodb```. Available languages are: actionscript, ada, applescript, bash, c, c#, c++, cpp, css, erlang, go, groovy, haskell, html, java, javascript, js, json, lua, none, nyan, objc, perl, php, python, r, rainbow, ruby, scala, sh, sql, swift, visualbasic, xml, yaml

  , wait and start it again.
  - Established early connections doesn't reconnect and writes tons errors - 

  Moped::Errors::ConnectionFailure

  . 
  - So I must restart application.
  
  I would have expected mongoid to attempt to reconnect automatically in this case without requiring a restart of the apps.
  
  My production.log:
  

  WARN - MOPED: Retrying connection attempt 60 more time(s). runtime: n/a
  ...
  WARN - MOPED: Retrying connection attempt 1 more time(s). runtime: n/a

FATAL - Moped::Errors::ConnectionFailure: Could not connect to a primary node for replica set #<Moped::Cluster:70042068689560 @seeds=[<Moped::Node resolved_address="000.000.000.000:27017">]>

My mongoid.yml: 

production:
sessions:
default:
database: newauto_data
hosts:

• 000.000.000.000:27017
  username: xxx
  password: yyy
  options:
  pool_size: 25
  max_retries: 60
  retry_interval: 1
  refresh_interval: 30
  `

I found issue 3 years old https://github.com/mongoid/mongoid/issues/794, but my case is new one.