Installed Ubuntu Server 20.04, but no Internet.

During the install of Ubuntu it gets to networking, where it reports no networking found.

• Tried with DHCP and with Static IP.
• The VM does get created but no networking on it.

Can ping the Proxmox host, but nothing else.

lspci | grep Ethernet

returns:

03:00.0 Ethernet controller: Intel Corporation Device 15f3 (rev 02)

On the Proxmox host:

brctl show

returns:

bridge name bridge id         STP enabled interfaces
vmbr0       8000.a8a1592fb8a6 no          enp3s0

udevadm info /sys/class/net/vmbr0

returns:

P: /devices/virtual/net/vmbr0
L: 0
E: DEVPATH=/devices/virtual/net/vmbr0
E: DEVTYPE=bridge
E: INTERFACE=vmbr0
E: IFINDEX=5
E: SUBSYSTEM=net
E: USEC_INITIALIZED=188415741
E: ID_NET_NAMING_SCHEME=v240
E: ID_NET_DRIVER=bridge
E: ID_NET_LINK_FILE=/usr/lib/systemd/network/99-default.link
E: ID_NET_NAME=eth0
E: SYSTEMD_ALIAS=/sys/subsystem/net/devices/eth0
E: TAGS=:systemd:

cat /usr/lib/systemd/network/99-default.link

returns:

#  SPDX-License-Identifier: LGPL-2.1+
#
#  This file is part of systemd.
#
#  systemd is free software; you can redistribute it and/or modify it
#  under the terms of the GNU Lesser General Public License as published by
#  the Free Software Foundation; either version 2.1 of the License, or
#  (at your option) any later version.
 
[Link]
NamePolicy=keep kernel database onboard slot path
MACAddressPolicy=persistent

journalctl -b -u systemd-networkd.service -u systemd-udevd.service --no-hostname

returns:

Mar 10 07:11:36 systemd[1]: Starting udev Kernel Device Manager...
Mar 10 07:11:36 systemd[1]: Started udev Kernel Device Manager.
Mar 10 07:11:36 systemd[1]: Starting Network Service...
Mar 10 07:11:36 systemd-udevd[296]: link_config: autonegotiation is unset or enabled, the speed and duplex are n
Mar 10 07:11:37 systemd-networkd[269]: Enumeration completed
Mar 10 07:11:37 systemd-networkd[269]: lo: Removing non-existent address: ::1/128 (valid forever), ignoring
Mar 10 07:11:37 systemd[1]: Started Network Service.
Mar 10 07:11:37 systemd-udevd[279]: Using default interface naming scheme 'v240'.
Mar 10 07:11:37 systemd-networkd[269]: eth0: Gained carrier
Mar 10 07:11:37 systemd-networkd[269]: eth0: Could not bring up interface: Invalid argument
Mar 10 07:11:37 systemd-networkd[269]: eth0: could not set address: Permission denied

	Supported ports: [ ]
	Supported link modes:   10baseT/Half 10baseT/Full 
	                        100baseT/Half 100baseT/Full 
	                        1000baseT/Full 
	                        2500baseT/Full 
	Supported pause frame use: Symmetric
	Supports auto-negotiation: Yes
	Supported FEC modes: Not reported
	Advertised link modes:  10baseT/Half 10baseT/Full 
	                        100baseT/Half 100baseT/Full 
	                        1000baseT/Full 
	                        2500baseT/Full 
	Advertised pause frame use: Symmetric
	Advertised auto-negotiation: Yes
	Advertised FEC modes: Not reported
	Speed: 1000Mb/s
	Duplex: Full
	Port: Twisted Pair
	PHYAD: 0
	Transceiver: internal
	Auto-negotiation: on
	MDI-X: off (auto)
	Current message level: 0x00000007 (7)
			       drv probe link
	Link detected: yes