[SOLVED] No connection or slow internet on VM under proxmox on a hetzner dedi

R

requests

New Member
Nov 15, 2020
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last reply made by me has the solution

Hi

So i cant get my linux vms to have internet access on my hetzner box.
If i try a windows vm they have stable and good connection it seems to be only linux.

I tried many distros, Ubuntu centos and debian.

im using hetzner subnets for my vms as a vmbr0 device

Code: 
auto vmbr0

iface vmbr0 inet static

  address [First useable ip from subnet]

  netmask 255.255.255.240

  bridge_ports none

  bridge_stp off

  bridge_fd 0



I hope you guys know a way to solve this issue
 
Last edited:
I'd be very surprised if it was an operating system problem that made Linux VM performance worse than Windows. As first step, it would make sense to really measure this. That means, running something like iperf3 between VMs and VM & Proxmox VE host
 
Dominic said:
I'd be very surprised if it was an operating system problem that made Linux VM performance worse than Windows. As first step, it would make sense to really measure this. That means, running something like iperf3 between VMs and VM & Proxmox VE host
Click to expand...
Its more like, when the vm with linux connects it has internet for a few seconds and then it no longer works until i restart the network interface (guest).
 
requests said:
Its more like, when the vm with linux connects it has internet for a few seconds and then it no longer works until i restart the network interface (guest).
Click to expand...
could it be an IP address conflict or so?
 
requests said:
dont think so no other vm is running on the ip and the ip doesnt respond to ping when vm is offline
Click to expand...
after restarting the network 1605534855178.png
after the 7 ping it stopped
I can ping the host without problems
 
Last edited:
can you post the output of following commands from your VM:
Code: 
ip a
ip r
cat /etc/network/interfaces
 
how have you configured the ubuntu VM network? it seems wrong. is this a NATted setup or with an additional IP?

maybe you can try traceroute 1.1.1.1 and post the output here (my guess is this is a routing issue)
 
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Reactions: Dominic
oguz said:
how have you configured the ubuntu VM network? it seems wrong. is this a NATted setup or with an additional IP?

maybe you can try traceroute 1.1.1.1 and post the output here (my guess is this is a routing issue)
Click to expand...
"how have you configured the ubuntu VM network? it seems wrong. is this a NATted setup or with an additional IP?"
im using nat im pretty sure.

first test
1605537213369.png

second test 1605537233020.png
third test

1605537254458.png
 
if you are using NAT setup then your ubuntu VM should have an IP for the internal subnet from your host bridge.

for example if you defined the bridge like so:
Code: 
auto vmbr0
iface vmbr0 inet static
        address 192.168.1.1/24
        bridge-ports none
        bridge-stp off
        bridge-fd 0

then your ubuntu VM network configuration should be something like,
Gateway: 192.168.1.1
IP: 192.168.1.10/24

i don't know how you configured it exactly because you didn't post your full /etc/network/intefaces from your PVE host.
 
oguz said:
if you are using NAT setup then your ubuntu VM should have an IP for the internal subnet from your host bridge.

for example if you defined the bridge like so:
Code: 
auto vmbr0
iface vmbr0 inet static
        address 192.168.1.1/24
        bridge-ports none
        bridge-stp off
        bridge-fd 0

then your ubuntu VM network configuration should be something like,
Gateway: 192.168.1.1
IP: 192.168.1.10/24

i don't know how you configured it exactly because you didn't post your full /etc/network/intefaces from your PVE host.
Click to expand...
the config from the host, i think im running bridge

Code: 
### Hetzner Online GmbH installimage

source /etc/network/interfaces.d/*

auto lo
iface lo inet loopback
iface lo inet6 loopback

auto enp98s0f0
iface enp98s0f0 inet static
  address 94.130.71.2
  netmask 255.255.255.192
  pointopoint 94.130.71.1
  gateway 94.130.71.1
  # route 94.130.71.0/26 via 94.130.71.1
  # up route add -net 94.130.71.0 netmask 255.255.255.192 gw 94.130.71.1 dev enp98s0f0

iface enp98s0f0 inet6 static
  address 2a01:4f8:10b:348c::2
  netmask 64
  gateway fe80::1

auto vmbr0
iface vmbr0 inet static
  address 178.63.114.16
  netmask 255.255.255.248
  bridge_ports none
  bridge_stp off
  bridge_fd 0
 
178.63.114.16 where does this IP come from? why don't you use a private IP range here instead?

this is likely causing routing errors...
 
requests said:
tried this but still not success
Click to expand...
what have you tried? how does your network configuration look like now? is the situation the same or any different?
 
oguz said:
what have you tried? how does your network configuration look like now? is the situation the same or any different?
Click to expand...
same issue, debian 10 and centos 8 have no issue seems to be only ubuntu

host config - proxmox

Code: 
### Hetzner Online GmbH installimage

source /etc/network/interfaces.d/*

auto lo
iface lo inet loopback
iface lo inet6 loopback

auto enp5s0
iface enp5s0 inet static
  address 88.198.64.35
  netmask 255.255.255.224
  gateway 88.198.64.33
  # route 88.198.64.32/27 via 88.198.64.33
  post-up echo 1 > /proc/sys/net/ipv4/ip_forward
  post-up echo 1 > /proc/sys/net/ipv4/conf/eno1/proxy_arp
  up route add -net 88.198.64.32 netmask 255.255.255.224 gw 88.198.64.33 dev enp5s0

iface enp5s0 inet6 static
  address 2a01:4f8:140:4478::2
  netmask 64
  gateway fe80::1

auto vmbr0
iface vmbr0 inet static
  address 178.63.204.240
  netmask 255.255.255.248
  bridge_ports none
  bridge_stp off
  bridge_fd 0

guest config - debian

Code: 
# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).

source /etc/network/interfaces.d/*

# The loopback network interface
auto lo
iface lo inet loopback

auto ens18
iface ens18 inet static
  address 178.63.204.241
  netmask 255.255.255.248
  pointopoint 88.198.64.35
  gateway 88.198.64.35

guest config - ubuntu

1606848765795.png
 
Last edited:
Solved it with this configuration:
Code: 
network:
  version: 2
  renderer: networkd
  ethernets:
    ens18:
     dhcp4: no
     addresses: [IP_OF_SUBNET/32]
     gateway4: GATEWAY
     nameservers:
       addresses: [8.8.8.8]
     routes:
       - to: GATEWAY/32
         via: 0.0.0.0
         scope: link
 
  • Like
Reactions: Deleted member 109343
requests said:
Solved it with this configuration:
Code: 
network:
  version: 2
  renderer: networkd
  ethernets:
    ens18:
     dhcp4: no
     addresses: [IP_OF_SUBNET/32]
     gateway4: GATEWAY
     nameservers:
       addresses: [8.8.8.8]
     routes:
       - to: GATEWAY/32
         via: 0.0.0.0
         scope: link
Click to expand...
Thanks! This also fixed connectivity for me with an OVH dedicated server.
 
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