Virtualbox Guest can't ping host, host can't connect to guest, other guests can ping/connect to guest [duplicate]

Question

My setup is as follows:

• Windows 10 Pro with one real (integrated) NIC enabled. The latest available Bonjour for Windows is installed
• Two virtual machines running Linux
• One other Windows laptop on the network

Let's call the Linux VMs A and B, and the two Windows devices X and Y. X is the VM host.

A can ping and connect to B, B can ping and connect to A.

X cannot connect to A or B, neither A or B can ping or connect to X. Y can connect to A and B and vice-versa.

This is not a firewall issue as nothing changes when the Windows Firewall is completely disabled on X.

Answer 1

Turns out this is a rather nasty bug in VirtualBox ~5.0.4. Forum comments suggest rolling back to 5.0.2 but it's unclear if this works for Windows versions greater than 7. There is an issue with the NDIS6 bridging driver. Workarounds that suggest forcing the NDIS5 adapter to be installed will not work in Windows 10.

See https://www.virtualbox.org/ticket/14457 and the possible working build

https://www.virtualbox.org/download/testcase/VirtualBox-5.0.5-102814-Win.exe. Treat this as a pre-alpha build.

Extension pack & guest additions can be found on https://www.virtualbox.org/wiki/Testbuilds

https://www.virtualbox.org/ticket/14457#comment:28 suggests this is not a long-term fix.