Email failing with network timeout

After I updated from v2.2.0.beta5 version ed546a0 to v2.2.0.beta6 version 6213e02, our outgoing mail stopped working. When I try to send a test mail, it tells me to check my app.yml, but that has not changed since early november this year but I tested the settings mentioned in the yaml file anyway and it checked out ok.
After sending a test mail, my production.log shows this:

Started POST "/admin/email/test" for 111.111.111.111 at 2018-12-29 07:40:29 +0000
Processing by Admin::EmailController#test as */*
Parameters: {"email_address"=>"xyz@gmail.com"}
Sent mail to xyz@gmail.com (30004.6ms)
Completed 422 Unprocessable Entity in 30062ms (Views: 0.5ms | ActiveRecord: 4.2ms)

error logs show this:

Job exception: execution expired

/usr/local/lib/ruby/2.5.0/net/smtp.rb:539:in `initialize' /usr/local/lib/ruby/2.5.0/net/smtp.rb:539:in `open' /usr/local/lib/ruby/2.5.0/net/smtp.rb:539:in `tcp_socket' /usr/local/lib/ruby/2.5.0/net/smtp.rb:549:in `block in do_start' /usr/local/lib/ruby/2.5.0/timeout.rb:103:in `timeout' /usr/local/lib/ruby/2.5.0/net/smtp.rb:548:in `do_start' /usr/local/lib/ruby/2.5.0/net/smtp.rb:518:in `start' /var/www/discourse/vendor/bundle/ruby/2.5.0/gems/mail-2.7.1.rc1/lib/mail/network/delivery_methods/smtp.rb:109:in `start_smtp_session' /var/www/discourse/vendor/bundle/ruby/2.5.0/gems/mail-2.7.1.rc1/lib/mail/network/delivery_methods/smtp.rb:100:in `deliver!' /var/www/discourse/vendor/bundle/ruby/2.5.0/gems/mail-2.7.1.rc1/lib/mail/message.rb:2159:in `do_delivery' /var/www/discourse/vendor/bundle/ruby/2.5.0/gems/mail-2.7.1.rc1/lib/mail/message.rb:260:in `block in deliver' /var/www/discourse/vendor/bundle/ruby/2.5.0/gems/actionmailer-5.2.2/lib/action_mailer/base.rb:560:in `block in deliver_mail' /var/www/discourse/vendor/bundle/ruby/2.5.0/gems/activesupport-5.2.2/lib/active_support/notifications.rb:168:in `block in instrument' /var/www/discourse/vendor/bundle/ruby/2.5.0/gems/activesupport-5.2.2/lib/active_support/notifications/instrumenter.rb:23:in `instrument' /var/www/discourse/vendor/bundle/ruby/2.5.0/gems/activesupport-5.2.2/lib/active_support/notifications.rb:168:in `instrument' /var/www/discourse/vendor/bundle/ruby/2.5.0/gems/actionmailer-5.2.2/lib/action_mailer/base.rb:558:in `deliver_mail' /var/www/discourse/vendor/bundle/ruby/2.5.0/gems/mail-2.7.1.rc1/lib/mail/message.rb:260:in `deliver' /var/www/discourse/vendor/bundle/ruby/2.5.0/gems/actionmailer-5.2.2/lib/action_mailer/message_delivery.rb:114:in `block in deliver_now' /var/www/discourse/vendor/bundle/ruby/2.5.0/gems/actionmailer-5.2.2/lib/action_mailer/rescuable.rb:17:in `handle_exceptions' /var/www/discourse/vendor/bundle/ruby/2.5.0/gems/actionmailer-5.2.2/lib/action_mailer/message_delivery.rb:113:in `deliver_now' /var/www/discourse/lib/email/sender.rb:197:in `send' /var/www/discourse/app/jobs/regular/user_email.rb:57:in `execute' /var/www/discourse/app/jobs/regular/critical_user_email.rb:14:in `execute' /var/www/discourse/app/jobs/base.rb:137:in `block (2 levels) in perform' /var/www/discourse/vendor/bundle/ruby/2.5.0/gems/rails_multisite-2.0.4/lib/rails_multisite/connection_management.rb:63:in `with_connection' /var/www/discourse/app/jobs/base.rb:127:in `block in perform' /var/www/discourse/app/jobs/base.rb:123:in `each' /var/www/discourse/app/jobs/base.rb:123:in `perform' /var/www/discourse/vendor/bundle/ruby/2.5.0/gems/sidekiq-5.1.3/lib/sidekiq/processor.rb:187:in `execute_job' /var/www/discourse/vendor/bundle/ruby/2.5.0/gems/sidekiq-5.1.3/lib/sidekiq/processor.rb:169:in `block (2 levels) in process' /var/www/discourse/vendor/bundle/ruby/2.5.0/gems/sidekiq-5.1.3/lib/sidekiq/middleware/chain.rb:128:in `block in invoke' /var/www/discourse/lib/sidekiq/pausable.rb:81:in `call' /var/www/discourse/vendor/bundle/ruby/2.5.0/gems/sidekiq-5.1.3/lib/sidekiq/middleware/chain.rb:130:in `block in invoke' /var/www/discourse/vendor/bundle/ruby/2.5.0/gems/sidekiq-5.1.3/lib/sidekiq/middleware/chain.rb:133:in `invoke' /var/www/discourse/vendor/bundle/ruby/2.5.0/gems/sidekiq-5.1.3/lib/sidekiq/processor.rb:168:in `block in process' /var/www/discourse/vendor/bundle/ruby/2.5.0/gems/sidekiq-5.1.3/lib/sidekiq/processor.rb:139:in `block (6 levels) in dispatch' /var/www/discourse/vendor/bundle/ruby/2.5.0/gems/sidekiq-5.1.3/lib/sidekiq/job_retry.rb:98:in `local' /var/www/discourse/vendor/bundle/ruby/2.5.0/gems/sidekiq-5.1.3/lib/sidekiq/processor.rb:138:in `block (5 levels) in dispatch' /var/www/discourse/vendor/bundle/ruby/2.5.0/gems/sidekiq-5.1.3/lib/sidekiq.rb:36:in `block in <module:Sidekiq>' /var/www/discourse/vendor/bundle/ruby/2.5.0/gems/sidekiq-5.1.3/lib/sidekiq/processor.rb:134:in `block (4 levels) in dispatch' /var/www/discourse/vendor/bundle/ruby/2.5.0/gems/sidekiq-5.1.3/lib/sidekiq/processor.rb:199:in `stats' /var/www/discourse/vendor/bundle/ruby/2.5.0/gems/sidekiq-5.1.3/lib/sidekiq/processor.rb:129:in `block (3 levels) in dispatch' /var/www/discourse/vendor/bundle/ruby/2.5.0/gems/sidekiq-5.1.3/lib/sidekiq/job_logger.rb:8:in `call' /var/www/discourse/vendor/bundle/ruby/2.5.0/gems/sidekiq-5.1.3/lib/sidekiq/processor.rb:128:in `block (2 levels) in dispatch' /var/www/discourse/vendor/bundle/ruby/2.5.0/gems/sidekiq-5.1.3/lib/sidekiq/job_retry.rb:73:in `global' /var/www/discourse/vendor/bundle/ruby/2.5.0/gems/sidekiq-5.1.3/lib/sidekiq/processor.rb:127:in `block in dispatch' /var/www/discourse/vendor/bundle/ruby/2.5.0/gems/sidekiq-5.1.3/lib/sidekiq/logging.rb:48:in `with_context' /var/www/discourse/vendor/bundle/ruby/2.5.0/gems/sidekiq-5.1.3/lib/sidekiq/logging.rb:42:in `with_job_hash_context' /var/www/discourse/vendor/bundle/ruby/2.5.0/gems/sidekiq-5.1.3/lib/sidekiq/processor.rb:126:in `dispatch' /var/www/discourse/vendor/bundle/ruby/2.5.0/gems/sidekiq-5.1.3/lib/sidekiq/processor.rb:167:in `process' /var/www/discourse/vendor/bundle/ruby/2.5.0/gems/sidekiq-5.1.3/lib/sidekiq/processor.rb:85:in `process_one' /var/www/discourse/vendor/bundle/ruby/2.5.0/gems/sidekiq-5.1.3/lib/sidekiq/processor.rb:73:in `run' /var/www/discourse/vendor/bundle/ruby/2.5.0/gems/sidekiq-5.1.3/lib/sidekiq/util.rb:16:in `watchdog' /var/www/discourse/vendor/bundle/ruby/2.5.0/gems/sidekiq-5.1.3/lib/sidekiq/util.rb:25:in `block in safe_thread'

In Sidekik I see email jobs being retried and never succeed. For instance:

Job: Jobs::CriticalUserEmail
Error: Jobs::HandledExceptionWrapper::WrappedNet::OpenTimeout: execution expired

I tried restarting discourse and even the entire machine, but no dice. Can anyone help me please? I am at a loss. I promise to migrate to the stable releases after this!