Hyper-V server 2019 – Internet not working for Guest VM - networking

Question

I’m new to Hyper-V, and I’m trying something apparently very simple:
Setup a Hyper-V 2019 server
On that server, install a Gen2 WM Windows server 2016
I have an identical hardware successfully running Hyper-V (and 2 VMs) as a role in Windows Server 2016 Standard. Therefore, that hardware is most likely to be fit for virtualization…. and as been ordered for that purpose only.
But I just can’t get the guest VM to connect to the network! I reviewed former posts about the subject, and did not find any solutions I did not yet already explored.
Setting up a Hyper-Server, and joining it to a domain was pretty straight forward. Event installing the VM was pretty simple.
Here is the current state, after I re-started from scratch (meaning reinstalled the computer from zero), and left the default, as generated by Microsoft:
The host does have access to internet (and is linked to AD) on ethernet NIC#1
Assigned Static IP: 192.168.0.96
Subnet: 255.255.255.0
gateway: 192.168.0.1
DNS: 192.168.0.1
From the remote Hyper-V manager, I did create a new Virtual Switch (only one)
Name: vSwitchExternXyz
Type: external
Linked to the external network using the same NIC#1
Allowed management operating system to share this network adapter (this is by default)
When executing an ipconfig" in command line on the host, I see a new “Ethernet adapter vEthernet (vSwitchExternXyz)” created, having:
Autoconfiguration IP4 Address: 169.254.197.61 (hey, this is a APIPA address !)
Subnet: 255.255.0.0
gateway: none!
From the remote Hyper-V manager, I did assign this vSwitchExternXyz Virtual Switch (the only one I created in the Host)
I left unchecked both options “Enable virtual LAN identification” and “Enable bandwidth management” (those are unchecked by default)
When I start & connect to that only VM, and look at it network config, I get:
Autoconfiguration IP4 Address: 169.254.224.167 (again another APIPA address!)
Subnet: 255.255.0.0
gateway: none!
From that picture, I’m not really surprised I cannot even ping any IP outside the APIPA address range, because the default gateway seems missing. I did try to assign it an IP and valid gateway (same as the host’s), but it made no differences. But I don’t know yet how should a successful configuration looks like.
Questions
I have no running environment to compare to in order to see if those defaults are correct. Do the virtual switch & VM’s vNIC adapter both should be given IP addresses?
Shouldn’t both virtual switch & VM’s vNIC adapter be in the same subnet than the host (meaning 192.168.0.x), and pointing to the same gateway?
What’s wrong with my VM to not access internet?

Answer 1

I resorted to Microsoft support to address this issues (it took 2 tech specialists 2.5 hours total to figure it out).
The problem was with the virtual switch which was corrupted for obscure reasons. It should have pick up the IP of the physical NIC.
It was not enough to just remove the vSwitch and re-create it.
I had to:
leave the faulty vSwitch there,
create a new vSwitch
Assign the new switch to the Guest VM's adapter
only then, delete the faulty vSwitch
Problem fixed, thanks to Raj at Microsoft technical support team.