[CentOS] After upgrade to CentOS 8.1 default gateway missing

On Thu, 16 Jan 2020 15:34:43 +0100, Stephen John Smoogen  
<smooge at gmail.com> wrote:

> On Thu, 16 Jan 2020 at 07:58, Asle Ommundsen <aommundsen at gmail.com>  
> wrote:
>>
>> Hi,
>>
>> Tonight I upgraded two CentOS 8 boxes to CentOS 8.1 (1911). Then after a
>> reboot of the first server the network was unavailable. In IPMI console
>> everything except the network was looking good. Network was unreachable.
>> No errors in NetworkManager. I also restarted NetworkManager, but it did
>> not help. Then I discovered that the default gateway suddenly was  
>> missing.
>>
>> Then I rebooted the server one more time, but network was still down.
>>
>> Then both myself and a technician in my datcenter was debugging this (I
>> had to wake him up in the middle of the night, costing me a lot of  
>> money),
>> without finding any reason for why the default gateway was missing after
>> reboot.
>>
>> Then we rebooted the server a third time, and all of a sudden the  
>> problem
>> was gone and the default gateway was back. [...cut...]

> In order to determine what is going on you need to give a lot more  
> information.
>
> 1. How do these boxes get their network information? DHCP or static
> 2. If they are static, what controls the setting of ips:
> NetworkManager or network-scripts
> 3. If they are static, how are they set in  
> /etc/sysconfig/network-scripts/
> 4. Do the files in /etc/sysconfig/network-scripts list a GATEWAY=
> 5. If you are using network-manager, what does nmtui or the graphical
> tool say the gateway or default route is?

Here is answers to your list. I have anonymized the some of the data:

1) Static ip configuration

2) This should be NetworkManager.
nmcli output:

eno1: connected to eno1
         inet4 1.1.1.234/29
         route4 1.1.1.232/29
         route4 0.0.0.0/0

eno2: connected to eno2
         inet4 192.168.0.5/24
         route4 192.168.0.0/24

[root at server ~]# nmcli d show | grep IP4.GATEWA
IP4.GATEWAY: 1.1.1.1.233

3)
TYPE=Ethernet
PROXY_METHOD=none
BROWSER_ONLY=no
BOOTPROTO=none
DEFROUTE=yes
IPV4_FAILURE_FATAL=yes
IPV6INIT=yes
IPV6_AUTOCONF=yes
IPV6_DEFROUTE=yes
IPV6_FAILURE_FATAL=no
IPV6_ADDR_GEN_MODE=stable-privacy
NAME=eno1
UUID=1f9ec889-3c64-470a-894b-05543ee44c29
DEVICE=eno1
ONBOOT=yes
IPADDR=1.1.1..234
PREFIX=29
GATEWAY=1.1.1.233
IPV6_PRIVACY=no

4) Yes

5)
[root at server ~]# nmcli d show | grep IP4.GATEWA
IP4.GATEWAY: 1.1.1.233

nmtui shows the same gateway.

Kind regards,
Asle Ommundsen