Hi,
I have a WS 2019 as a host and two VMs running on the hyper-v, one ubuntu and one windows 7. The host has a network bridge set up, which contains a number of ethernet interfaces (one of which connects to a router that links to the internet) and a virtual switch from hyper-v. The two VMs are connected to this virtual switch (in hyper-v manager, this is set up as an internal switch).
Now the problem is that, although both VMs have external network access (internet), and all other machines on the network can connect with these VMs, the host cannot communicate with either VM. If I ping from the host to either VM or ping from either VM to the host, it reports Destination Host Unreachable. Note that DNS works fine but they cannot access each other even using the IP address. Weirdly, this setup had been working perfectly in the past but only very recently stopped working. I really don't know what has happened.
Troubleshooting steps performed include: restarting the host, restarting the guests, resetting the network bridge, removing the virtual switch from the bridge and adding it back, deleting the virtual switch and creating another one, disabling the virtual switch and re-enabling it, renewing DHCP lease, and restarting the router. I feel I have run out of ideas. Any help/idea is really appreciated!
Edit 1: I tried to arp -a in the Ubuntu VM and found that the MAC address of the host is "incomplete". arp -a in the Windows 7 VM gives no record of the host, and arp -a in the host gives no record of either of the VMs.