SolusIO VPS looses network connectivity after restart

Symptoms 

• After VPS restart network connectivity is lost. CentOS 7/8 looses IPv6 connectivity, Ubuntu 18/20 looses both IPv4 and IPv6 connectivity.
• Inside a VPS IPv6 address ip a command shows the following status for IPv6 address:

  CONFIG_TEXT: inet6 2001:db8:f61:a1ff:0:0:0:80/64 scope global tentative dadfailed

Cause

VPS sends Duplicate Address Detection(DAD) request. CR receives the request on br-routed interface and responds that there is such IPv6 address. VPS receives the response from br-routed and turns the IPv6 address off.

Resolution

1. Connect to CR via SSH 
2. Run the command:

   # ovs-vsctl set bridge br-routed stp_enable=true

In order for settings to be applied on reboot and network or network interface restart it is necessary to modify the interface configuration file on CR.

On Debian 10, Ubuntu 18, Ubuntu 20 CR modify the configuration file /etc/network/interfaces for br-routed part with the following content:

CONFIG_TEXT: ...
auto br-routed
allow-ovs br-routed
allow-hotplug br-routed
iface br-routed inet manual
        ovs_type OVSBridge
        ovs_extra set bridge br-routed stp_enable=true
...

On Centos 7/8 CR modify the file /etc/sysconfig/network-scripts/ifcfg-br-routed with the following content:

CONFIG_TEXT: # Generated by solus
DEVICE=br-routed
ONBOOT=yes
NM_CONTROLLED=no
TYPE=OVSBridge
DEVICETYPE=ovs
OVS_EXTRA="set bridge br-routed stp_enable=true"