SME Server 9.2 Addendum
No external network access when using bonding
If you are using bonding of two network interfaces (e.g. server-only mode with two indentical network adapters) the default route to the gateway is not created. to check if you have any bonding on your server:
# ifconfig |grep bond
If it returns something then you have bonding. This is fixed in e-smith-base-5.6.0-31 available in smeupdates since May the 4th, 2017. You can use 'yum update' to upgrade to this latest version of e-smith-base.
If you upgraded from SME Server 9.1 to 9.2.0 and do not have a network connection, you should perform the following:
route add default gateway `db configuration get GatewayIP` yum update e-smith-base signal-event post-upgrade; signal-event reboot
Replace `db configuration get GatewayIP` by your gateway IP if you know it, but this command should give the value you previously configured).