環境

macOS Catalina 10.15.6
Vagrant 2.2.10
Virtualbox 6.1.14

Vagrantfile

Vagrant.configure("2") do |config|
  config.vm.box = "ubuntu/trusty64"
  config.vm.provider "virtualbox" do |vb|
    vb.customize ["modifyvm", :id, "--cableconnected1", "on"]
  end
end

初回起動時

❯ vagrant up
Bringing machine 'default' up with 'virtualbox' provider...
==> default: Importing base box 'ubuntu/trusty64'...
==> default: Matching MAC address for NAT networking...
==> default: Checking if box 'ubuntu/trusty64' version '20190514.0.0' is up to date...
==> default: Setting the name of the VM: vagrant_default_1601222138683_16202
==> default: Clearing any previously set forwarded ports...
==> default: Clearing any previously set network interfaces...
==> default: Preparing network interfaces based on configuration...
    default: Adapter 1: nat
    default: Adapter 2: hostonly
==> default: Forwarding ports...
    default: 22 (guest) => 2222 (host) (adapter 1)
==> default: Running 'pre-boot' VM customizations...
==> default: Booting VM...
==> default: Waiting for machine to boot. This may take a few minutes...
    default: SSH address: 127.0.0.1:2222
    default: SSH username: vagrant
    default: SSH auth method: private key
    default: 
    default: Vagrant insecure key detected. Vagrant will automatically replace
    default: this with a newly generated keypair for better security.
    default: 
    default: Inserting generated public key within guest...
    default: Removing insecure key from the guest if it's present...
    default: Key inserted! Disconnecting and reconnecting using new SSH key...
==> default: Machine booted and ready!
==> default: Checking for guest additions in VM...
    default: The guest additions on this VM do not match the installed version of
    default: VirtualBox! In most cases this is fine, but in rare cases it can
    default: prevent things such as shared folders from working properly. If you see
    default: shared folder errors, please make sure the guest additions within the
    default: virtual machine match the version of VirtualBox you have installed on
    default: your host and reload your VM.
    default: 
    default: Guest Additions Version: 4.3.40
    default: VirtualBox Version: 6.0
==> default: [vagrant-hostsupdater] Checking for host entries
==> default: Configuring and enabling network interfaces...
==> default: Mounting shared folders...
    default: /vagrant => /Users/takaaki/Develop/vagrant

再起動時

default: [vagrant-hostsupdater] Removing hosts
==> default: Attempting graceful shutdown of VM...
==> default: Checking if box 'ubuntu/trusty64' version '20190514.0.0' is up to date...
==> default: Clearing any previously set forwarded ports...
==> default: Clearing any previously set network interfaces...
==> default: Preparing network interfaces based on configuration...
    default: Adapter 1: nat
    default: Adapter 2: hostonly
==> default: Forwarding ports...
    default: 22 (guest) => 2222 (host) (adapter 1)
==> default: Running 'pre-boot' VM customizations...
==> default: Booting VM...
==> default: Waiting for machine to boot. This may take a few minutes...
    default: SSH address: 127.0.0.1:2222
    default: SSH username: vagrant
    default: SSH auth method: private key
    default: Warning: Connection reset. Retrying...
    default: Warning: Remote connection disconnect. Retrying...

永遠に接続にできずにタイムアウトになります

解決策

仮想サーバー構築時に

default: The guest additions on this VM do not match the installed version of

とログ出力されていたので

❯ vagrant plugin install vagrant-vbguest
❯ vagrant vbguest

上記のコマンドでプラグインをインストールしguest additionsのバージョンを合わせたら再起動して接続できるようになりました