Proxmox/ESXi Comcast no DHCP IP

I am running VyOS on Proxmox (was previously running on ESXi with the same issue). I have a Comcast residential circuit and I am unable to get a DHCP address in my VM. A packet capture shows the DHCPDISCOVERs leaving the host, but the reply apparently never makes it to the VM. I see the MAC addresses on both the cable modem and the VM in the correct VLAN of my switch.

Googling found this post: but the answer is on the Vyatta forum which is offline.

Has anyone ran into this before?

I use proxmox and any vm can get ip address over dhcp.
Can you describe more details? What you do?
Do you use pass through from some link to vm?
Is it problem only with vyos or any other vm have same behaviour?

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Hi Viacheslav,
Thank you for your response.

It seems to only be an issue for VMs requesting DHCP from my Comcast connection. I’ve seen this issue with both VyOS and the Sophos XG virtual appliance. It has also been an issue on both Proxmox and VMware ESXi. Any VM on the host that requests a DHCP address from my standalone router receives it right away.

The cable modem is an Arris SB8200. It connects to an access port on my Juniper EX2200 switch. From there, I trunk the VLAN over an aggregated Ethernet bundle to my Proxmox host. The Linux bond is part of a VLAN aware Linux bridge to which the VyOS VM is attached. On that VM, I have a VyOS VIF that is associated with my WAN VLAN.

If I check the MAC address table on the Juniper switch I can see both the MAC address of the modem and the MAC address of the VM. When I run a packet capture from with VyOS, I see the DHCPDISCOVER leaving the host. I’ve also seen the DHCPDISCOVER packets coming out of the server when running a packet capture attached to the server NIC. I need to re-run the packet capture from a switch mirror port to see whether or not the modem is returning any offers (I am not seeing them when running the capture on the VyOS VM). As soon as I connect the modem to a VyOS instance running on bare metal, VyOS gets an address straight away.

Try to check, maybe proxmox host (or other device in same vlan) gets this IP address via DHCP instead of VM host?
Another issue that can be it lease option on the ISP site, if it save mac address from old lease session.

The modem could be binding to the very first MAC address it sees on the wire, such as BDPU packets from the switch, and not the VyOS MAC address even though the VM sends the first DHCP request. Try disabling STP, keep alive, and all discovery features on the switch port and VLAN connected to the modem.