Okay just to make sure:About SDN.
I've two guest Proxmox VMs running on my main host. The guest Proxmox VMs get their IPs correctly from the same DHCP as main host. So, maybe it's ok the SDN and the error comes from elsewhere.
However, I cannot start any VMs inside these guest Proxmox instances. It seems to be failing due to a dnsmasq error.
Code:org.freedesktop.DBus.Error.ServiceUnknown: The name uk.org.thekelleys.dnsmasq.Beta was not provided by any .service files kvm: -netdev type=tap,id=net0,ifname=tap102i0,script=/var/lib/qemu-server/pve-bridge,downscript=/var/lib/qemu-server/pve-bridgedown,vhost=on: network script /var/lib/qemu-server/pve-bridge failed with status 2816 TASK ERROR: start failed: QEMU exited with code 1
Is your main host also a Proxmox VE Node and we're talking about nested virtualization?
Have you configured the SDN DHCP feature in your Proxmox VE guests, so that their guests get IP addresses from them?
If I have misunderstood your setup, please elaborate.
Can you please share the dnsmasq error message with us?