Hyper-V Guest on Windows 11 has lost visibility to host

Question

Puzzled with a recent update that stopped my working VM’s from talking to the Hyper-V host.

Updates that were installed and the dates:
KB4023057 (18-02-2022)
KB5010414 (16-02-2022)

Host build:
Windows 11 Pro 21H2 OS Build 22000.527

Setup:
Main host PC is running Hyper-V and had a working VM on a dedicated IP address. This was using a virtual switch, set to internal, so that I could use the same IP range from the DHCP services on my router.
All working perfectly fine – I was able to ping host to guest, and guest to host. Firewall rules setup to allow this.
I also had an IIS API service running, that the guest could browse to and ping – that’s now stopped working.

Guest VM:
Set to a static IP address
IPv4 Address: 10.10.0.30(Preferred)
Subnet Mask: 255.255.255.0
Default Gateway: 10.10.0.1

Host:
IPv4 Address: 10.10.0.26(Preferred)
Subnet Mask: 255.255.255.0
Default Gateway: 10.10.0.1

Since the install of the updates, this has failed - I can no longer browse from guest to host.
I have replicated the same setup on another local host – so enabled the Hyper-V features (Tools and Platform) as well as Virtual Machine platform.

Host is setup as per the ipconfig below

Windows IP Configuration
Host Name . . . . . . . . . . . . : Titan
Primary Dns Suffix . . . . . . . :
Node Type . . . . . . . . . . . . : Hybrid
IP Routing Enabled. . . . . . . . : No
WINS Proxy Enabled. . . . . . . . : No

Ethernet adapter vEthernet (Titan_Internal):
Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : Hyper-V Virtual Ethernet Adapter #2
Physical Address. . . . . . . . . : 00-15-5D-00-0A-00
DHCP Enabled. . . . . . . . . . . : No
Autoconfiguration Enabled . . . . : Yes
Link-local IPv6 Address . . . . . : fe80::d589:fdf6:414a:a7ef%35(Preferred)
IPv4 Address. . . . . . . . . . . : 10.10.0.90(Preferred)
Subnet Mask . . . . . . . . . . . : 255.255.255.0
Default Gateway . . . . . . . . . :
DHCPv6 IAID . . . . . . . . . . . : 587208029
DHCPv6 Client DUID. . . . . . . . : 00-01-00-01-27-00-63-33-B4-2E-99-E5-3E-26
NetBIOS over Tcpip. . . . . . . . : Enabled

Ethernet adapter Ethernet:
Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : Realtek PCIe GbE Family Controller
Physical Address. . . . . . . . . : B4-2E-99-E5-3E-26
DHCP Enabled. . . . . . . . . . . : No
Autoconfiguration Enabled . . . . : Yes
Link-local IPv6 Address . . . . . : fe80::fc8a:591d:83eb:e0d%11(Preferred)
IPv4 Address. . . . . . . . . . . : 10.10.0.10(Preferred)
Subnet Mask . . . . . . . . . . . : 255.255.255.0
Default Gateway . . . . . . . . . : 10.10.0.1
DHCPv6 IAID . . . . . . . . . . . : 380907161
DHCPv6 Client DUID. . . . . . . . : 00-01-00-01-27-00-63-33-B4-2E-99-E5-3E-26
DNS Servers . . . . . . . . . . . : 8.8.8.8
8.8.8.8
DoH: https://dns.google/dns-query
8.8.4.4
8.8.4.4
DoH: https://dns.google/dns-query
NetBIOS over Tcpip. . . . . . . . : Enabled

Ethernet adapter vEthernet (Default Switch):
Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : Hyper-V Virtual Ethernet Adapter
Physical Address. . . . . . . . . : 00-15-5D-14-B9-BD
DHCP Enabled. . . . . . . . . . . : No
Autoconfiguration Enabled . . . . : Yes
Link-local IPv6 Address . . . . . : fe80::3d00:b707:c44c:bf33%29(Preferred)
IPv4 Address. . . . . . . . . . . : 172.21.112.1(Preferred)
Subnet Mask . . . . . . . . . . . : 255.255.240.0
Default Gateway . . . . . . . . . :
DHCPv6 IAID . . . . . . . . . . . : 486544733
DHCPv6 Client DUID. . . . . . . . : 00-01-00-01-27-00-63-33-B4-2E-99-E5-3E-26
NetBIOS over Tcpip. . . . . . . . : Enabled

Guest VM (On new install)

Windows IP Configuration
Host Name . . . . . . . . . . . . : VM-TITAN
Primary Dns Suffix . . . . . . . :
Node Type . . . . . . . . . . . . : Hybrid
IP Routing Enabled. . . . . . . . : No
WINS Proxy Enabled. . . . . . . . : No

Ethernet adapter Ethernet:
Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : Microsoft Hyper-V Network Adapter
Physical Address. . . . . . . . . : 00-15-5D-00-0A-01
DHCP Enabled. . . . . . . . . . . : No
Autoconfiguration Enabled . . . . : Yes
Link-local IPv6 Address . . . . . : fe80::61d1:42a0:a955:4840%9(Preferred)
IPv4 Address. . . . . . . . . . . : 10.10.0.80(Preferred)
Subnet Mask . . . . . . . . . . . : 255.255.255.0
Default Gateway . . . . . . . . . : 10.10.0.90
DHCPv6 IAID . . . . . . . . . . . : 100668765
DHCPv6 Client DUID. . . . . . . . : 00-01-00-01-29-A3-B5-F6-00-15-5D-00-0A-01
DNS Servers . . . . . . . . . . . : 10.10.0.90
NetBIOS over Tcpip. . . . . . . . : Enabled

After a bit of research, I found that I had to configure the Ethernet adapter vEthernet (Titan_Internal) to have it’s own IP address and Subnet, and not Gateway.

This then meant that the Guest VM could use a static IP address, and the host VM Ethernet adapter vEthernet (Titan_Internal) IP as the gateway – this established “Network 2” on the Guest, and I could ping that from the host.
But still not Guest to host.

Any ideas welcome! I set it up this way as I didn’t want the VM’s to use the Default Switch and have NAT 172.x.x.x addresses.

As I said, prior to the updates, this was working fine, but now isn’t.
Thanks!

Answer 1

On the actual adaptor itself, it's no longer got IPv4 box ticked (or some others, but it does have "Hyper-V Extensible Virtual Switch)

Normal and expected behavior. When you create a new external vSwitch the internet protocols are removed from the adapter and the Hyper-V Extensible Switch protocol is added turning that physical port into a multi-port virtual switch.

still can't get from the Guest to Host to ping

By default ICMPv4 is blocked through windows firewall

--please don't forget to upvote and Accept as answer if the reply is helpful--

Answer 2

was using a virtual switch, set to internal, so that I could use the same IP range from the DHCP services on my router.

Actually should be using an external vSwitch
https://learn.microsoft.com/en-us/archive/blogs/jhoward/hyper-v-what-are-the-uses-for-different-types-of-virtual-networks

Also note:
https://support.microsoft.com/en-us/topic/how-multiple-adapters-on-the-same-network-are-expected-to-behave-e21cb201-2ae1-462a-1f47-1f2307a4d47a

--please don't forget to upvote and Accept as answer if the reply is helpful--

Answer 3

Same issue happened to me today after windows 11 was updated. Everything was working fine before. The updates were

https://support.microsoft.com/en-us/topic/kb5012170-security-update-for-secure-boot-dbx-72ff5eed-25b4-47c7-be28-c42bd211bb15

https://support.microsoft.com/en-us/topic/kb4023057-update-for-windows-update-service-components-fccad0ca-dc10-2e46-9ed1-7e392450fb3a

Both are part of Windows 11, version 22H2 update.