Rails server suddenly not responding

Question

My Rails 4.2.6 production server worked perfectly for long time. Today I've added some functionality & migrated the server, everything looked fine until after some time of using the application the server become unresponsive.

The logs looks fine, the last request to the server worked without any errors, and the server still running but not unsering any requests.

Any clues? directions?

EDIT:

Looking at the docker logs I can see some errors on SSL:

[2017-06-07 15:06:10] ERROR OpenSSL::SSL::SSLError: SSL_accept SYSCALL returned=5 errno=0 state=unknown state
        /usr/local/lib/ruby/2.3.0/openssl/ssl.rb:401:in 'accept'

P.S. on of the main updates in the application is adding SSL certificate to the application.