rails tutorialの1.3.2でサーバーが起動しません。

前提・実現したいこと

初めて投稿させていただきます。
現在cloud９上でrails tutorialで学習し始めたのですが、早速つまずいてしまいました。。
チュートリアルの内容に沿って進めてターミナルにrails server -b $IP -p $PORTと入力すると以下のようになります。

下のメッセージはshareからapplicationのURL？を開いた場面です。

発生している問題・エラーメッセージ

Oops
Error: 1 validation error detected: Value '18.188.129.218' at 'envi...
Try refreshing the page. If it still doesn’t work in 5-10 minutes, please contact support.

該当のソースコード

ec2-user:~/environment $ ls
hello_app  README.md
ec2-user:~/environment $ cd hello_app/
ec2-user:~/environment/hello_app $ rails server -b $IP -p $PORT
=> Booting WEBrick
=> Rails 4.2.2 application starting in development on http://127.0.0.1:8080
=> Run `rails server -h` for more startup options
=> Ctrl-C to shutdown server
/usr/local/rvm/gems/ruby-2.4.1/gems/activesupport-4.2.2/lib/active_support/core_ext/numeric/conversions.rb:121: warning: constant ::Fixnum is deprecated
/usr/local/rvm/gems/ruby-2.4.1/gems/activesupport-4.2.2/lib/active_support/core_ext/numeric/conversions.rb:121: warning: constant ::Bignum is deprecated
Exiting
/usr/local/rvm/gems/ruby-2.4.1/gems/activesupport-4.2.2/lib/active_support/core_ext/numeric/conversions.rb:124:in `block (2 levels) in <class:Numeric>': stack level too deep (SystemStackError)
        from /usr/local/rvm/gems/ruby-2.4.1/gems/activesupport-4.2.2/lib/active_support/core_ext/numeric/conversions.rb:131:in `block (2 levels) in <class:Numeric>'
        from /usr/local/rvm/gems/ruby-2.4.1/gems/activesupport-4.2.2/lib/active_support/core_ext/numeric/conversions.rb:131:in `block (2 levels) in <class:Numeric>'
        from /usr/local/rvm/gems/ruby-2.4.1/gems/activesupport-4.2.2/lib/active_support/core_ext/numeric/conversions.rb:131:in `block (2 levels) in <class:Numeric>'
        from /usr/local/rvm/gems/ruby-2.4.1/gems/activesupport-4.2.2/lib/active_support/core_ext/numeric/conversions.rb:131:in `block (2 levels) in <class:Numeric>'
        from /usr/local/rvm/gems/ruby-2.4.1/gems/activesupport-4.2.2/lib/active_support/core_ext/numeric/conversions.rb:131:in `block (2 levels) in <class:Numeric>'
        from /usr/local/rvm/gems/ruby-2.4.1/gems/activesupport-4.2.2/lib/active_support/core_ext/numeric/conversions.rb:131:in `block (2 levels) in <class:Numeric>'
        from /usr/local/rvm/gems/ruby-2.4.1/gems/activesupport-4.2.2/lib/active_support/core_ext/numeric/conversions.rb:131:in `block (2 levels) in <class:Numeric>'
        from /usr/local/rvm/gems/ruby-2.4.1/gems/activesupport-4.2.2/lib/active_support/core_ext/numeric/conversions.rb:131:in `block (2 levels) in <class:Numeric>'
         ... 5007 levels...
        from /home/ec2-user/environment/hello_app/bin/spring:15:in `require'
        from /home/ec2-user/environment/hello_app/bin/spring:15:in `<top (required)>'
        from bin/rails:3:in `load'
        from bin/rails:3:in `<main>'