guests cannot ping LAN

[freesbee]

Hi!

I have a very strange situation. None of my guests can ping the LAN.
Network adapters are set as Bridged Adapter and one month ago all guests on this system were working fine (everything could ping everything).
Now I have guests able to ping only the host and the other guests.
The host can ping everything.
A computer on the LAN CON ping the host but CANNOT ping the guests (one month ago it was possible).
My guests CAN ping the host but CANNOT ping the LAN (also this was possible one month ago).

Upgrading to 5.2.0 doesn't help.
Host is Win10 1703 x64
Guests are various systems (Win7, Win Server 2012R2...)
Disabling firewalls does not have any effect.

I finished my ideas

[socratis]

Can you make sure that the Bridged filters have been installed? Network adapters, properties. And please try to reinstall using the following method:

1. Uninstall VirtualBox. Your VMs are going to be untouched. Reboot.
2. You may want to clean up your registry and/or filesystem at this point. CCleaner is a freeware utility that could help you. Mind the installation, it comes with "offers" from 3rd parties, known as "bundleware". Also, check out Device Cleanup program that helps you to remove any unused devices from your computer.
3. Download (if you haven't already) the latest VirtualBox and its matching ExtPack. Store them in a common location, i.e. not on "Desktop", or "Documents", but to "Public/Downloads" for example.
4. Locate the downloaded file in Windows Explorer. Right-click on the installer and select "Run-as-Administrator", even if you are the administrator. At the end of the installation, choose to "Start Oracle VM VirtualBox". Do not worry if your VMs do not show up.
5. If you're going to install the ExtPack, go to File » Preferences » Extensions. Click on the icon with the orange, down-pointing arrow on the right. Select the ExtPack from the previous steps.
6. Quit VirtualBox. Re-start VirtualBox as you would normally, i.e. from the Desktop shortcut or the Start menu.
7. Update the Guest Additions (GAs) in your guest(s), if the GAs are available for a specific guest.