Vagrant can't connect to the VM - ssh

Question

EDIT6: submitted an official path bug: https://github.com/mitchellh/vagrant/issues/7512
EDIT5: When I do vagrant destroy and vagrant up, everything works easily. But when I turn off the VM and turn it back on (you have to restart your PC some day), it won't work again. Either the sequence for vagrant up when the VM is created is bugged or VirtualBox is bugged. Destroying and rebuilding the VM is not the option, cause the DB migration and everything takes ~30 mins at least. Either way, DON'T USE VAGRANT ON WINDOWS 10.
EDIT4: I downgraded to Virtual Box 5.0.0.10, that fix the wrong path problem, but the error Command not in installer persists.
EDIT3: When I went into vagrant up --debug, I found out that it cycles. It gets into line
INFO subprocess: Starting process: ["C:/Program Files/Oracle/VirtualBox/VBoxManage.exe", "showvminfo", "8aaee3a3-806f-4
8ad-9928-91e2b7baba5d", "--machinereadable"]
and then it does
INFO subprocess: Command not in installer, restoring original environment...
The path to VM uses forwards slashes instead of backslashes. Is this a bug? Is there a way to manually set path to VM? I have put C:\Program Files\Oracle\VirtualBox in my PATH.
EDIT2: DON'T USE VAGRANT ON WINDOWS 10, it's bugged in many ways, also VM is not optimalized for win10 yet, you'll get bunch of issues that you won't be able to solve. Also tried the Otto from Hashicorp, not working either. Rip.
EDIT: okay, so when I do vagrant destroy and vagrant up, after 10 minutes of installation it works like a charm. But after I restart my PC or logout in any way, Vagrant is unable to connect to the VM, neither with a private key, nor with login/password. Is that a bug?
When I do vagrant up, VM starts properly, but Vagrant is unable to connect. All it says is Warning: Remote connection disconnect. Retrying...
When I try to connect via vagrant ssh, I get only ssh_exchange_identification: read: Connection reset by peer. When I check GUI of the VM, it is waiting for login, and when I login with defult login/password, it is working as intended, so the problem must be Vagrant not being able to connect to the VM.
I tried:
checking if my pc supports virtualization and checking if it is on
trying to connect with password instead of a key
configuring networking adapetrs
turning off firewall
clean reinstall
I am using Vagrant 1.8.1 and VirtualBox 5.0.20 on Windows 10.
This is my vagrant file:
VAGRANTFILE_API_VERSION = "2"
Vagrant.configure(VAGRANTFILE_API_VERSION) do |config|
config.vm.box = "ubuntu/trusty64"
config.vm.provider :virtualbox do |vb|
vb.memory = 2048
vb.gui = true
vb.cpus = 2
end
config.vm.network :private_network, type: "dhcp"
config.vbguest.auto_update = false
config.ssh.insert_key = false
config.vm.provision :shell, path: "bootstrap.sh"
end

Answer 1

[Edit 17/06/2016]
The problem should be resolved with Virtualbox 5.0.22.
https://www.virtualbox.org/wiki/Changelog
https://www.virtualbox.org/ticket/15412
[Original answer below]
In contrast to my earlier answer I now don't think that I encounter the same problem as you have described here. However I still think that you encounter a different variation the problem.
As of feedback received from Virtualbox development https://www.virtualbox.org/ticket/15412 I learned that Virtualbox 5.0.20 includes changes to the NAT Forwarding Rules to address other bugs. When a VM is saved and started again, Virtualbox now removes the network cable for 5 seconds. This is supposed to trigger the DHCP client to request a new lease. This information in turn is then used by Virtualbox to infer the IP address and NAT should work.
In my particular case I encounter this problem with Ubuntu 16.04 as guest VM whereas with Ubuntu 14.04 it works. This indicates to me that the DHClient on Ubuntu 14.04 does request a new lease after the cable was disconnected by Virtualbox whereas this is not the case with Ubuntu 16.04.
In order to verify that you encounter the same problem, I wonder if you could run the below test and let me know.
Login to the Trusty VM console (i.e. the one that you get displayed when you run the VM in the foreground)
Install 'arping' (sudo apt-get -y install arping)
Create the below script 'sendARP.sh'
#!/bin/bash
IFACE=$(ifconfig | grep 'Link encap:Ethernet' | awk '{print $1}')
IP=$(ifconfig | grep -Eo 'inet (addr:)?([0-9]*\.){3}[0-9]*' | grep -Eo '([0-9]*\.){3}[0-9]*' | grep -v '127.0.0.1')
arping -c 1 -i $IFACE $IP
Make it an executable 'chmod +x sendARP.sh'
Save the Trusty VM (vagrant suspend)
Start your Trusty VM from saved state (vagrant up)
Login to the Trusty VM console (i.e. the one that you get displayed when you run the VM in the foreground)
Run the script 'sudo ./sendARP.sh'
Test whether you can connect via SSH from the remote location/ Virtualbox host
Bugs:
https://github.com/mitchellh/vagrant/issues/7306
https://www.virtualbox.org/ticket/15412